Cold cathode field emission display

ABSTRACT

A cold cathode field emission display comprising a cathode panel CP having a plurality of cold cathode field emission devices and an anode panel AP which panels are bonded to each other in their circumferential portions, the anode panel AP comprising a substrate  30 , a phosphor layer  31  formed on the substrate  30 , an anode electrode  35  formed on the phosphor layer  31  and a resistance layer  36  for controlling a discharge current, the resistance layer  36  formed on the anode electrode  35  and having a thickness of t R  (unit: μm), and the cold cathode field emission display satisfying the following expression, where “C” represents an electrostatic capacity (F) between the cold cathode field emission device and the anode electrode, and “V A ” is a voltage (V) applied to the anode electrode
 
 t   R ×10 −2 &gt;(½) C·V   A   2 .

TECHNICAL FIELD

The present invention relates to a cold cathode field emission displaycharacterized in an anode electrode formed in an anode panel or a focuselectrode provided in a cold cathode field emission device formed on acathode panel.

BACKGROUND ART

In the fields of displays for use in television receivers andinformation terminals, studies have been made for replacing conventionalmainstream cathode ray tubes (CRT) with flat-panel displays which are tocomply with demands for a decrease in thickness, a decrease in weight, alarger screen and a high fineness. Such flat panel displays include aliquid crystal display (LCD), an electroluminescence display (ELD), aplasma display panel (PDP) and a cold cathode field emission display(FED). Of these, a liquid crystal display is widely used as a displayfor an information terminal. For applying the liquid crystal display toa floor-type television receiver, however, it still has problems to besolved concerning a higher brightness and an increase in size. Incontrast, a cold cathode field emission display (to be sometimesreferred to as “display” hereinafter) uses cold cathode field emissiondevices (to be sometimes referred to as “field emission device”hereinafter) capable of emitting electrons from a solid into a vacuum onthe basis of a quantum tunnel effect without relying on thermalexcitation, and it is of great interest from the viewpoints of a highbrightness and a low power consumption.

As one example of the above field emission device, FIG. 26 shows aschematic partial end view of a filed emission device as shown in FIG. 2to JP-A-9-90898.

In this field emission device, an insulating layer 2 is deposited on asubstrate 1, and a control electrode (gate electrode) 3 made of a metalthin film is stacked on the insulating layer 2. A single cavity (openingportion) or a plurality of cavities (opening portions) is/are formed inthe insulating layer 2 and the control electrode 3, and an emitter(electron emitting portion) 4 having the form of a cone is formedtherein. An insulating layer 5 and a focus electrode 6 are stacked onthe control electrode 3 excluding vicinities of the emitter 4. Thesubstrate 1, the insulating layer 2, the control electrode 3, theemitter 4, the insulating layer 5 and the focus electrode 6 constitute amicro cold cathode (field emission device) 7, and a single micro coldcathode or a plurality of micro cold cathodes constitutes or constitutea cold cathode 15. In effect, electron beams 8 emitted from the emitter(electron emitting portion) 4 collide with an anode (anode electrode) 9,and flow in an anode-electrode power source (anode-electrode controlcircuit) 10 that generates positive voltage.

A voltage to be applied to the control electrode (gate electrode) 3 isgenerated in a control-electrode power source (gate-electrode controlcircuit) 17, and a voltage obtained by potential-dividing the voltage tobe applied to the control electrode 3 with a variable resistor isapplied to the focus electrode 6. As a result, the ratio of the voltageof the control electrode 3 and the voltage of the focus electrode 6 isconstantly maintained at a value set with the variable resistor 14. Whenthe focus state in a certain beam current quantity is adjusted with thevariable resistor 14, a nearly equivalent focus state is maintained evenif the electron beam current set value taken out from the emitter 4 ischanged with an output voltage of the control electrode power source 17.

Meanwhile, in such a display, the distance between the anode (anodeelectrode) 9 and the focus electrode 6 is approximately 1 mm at thelargest, and an abnormal discharge (vacuum arc discharge) is likely tooccur between the anode 9 and the focus electrode 6. When an abnormaldischarge occurs, the voltage of the focus electrode 6 or the controlelectrode (gate electrode) 3 abnormally increases, so that displayperformance is impaired in display quality, and further that the fieldemission device (control electrode 3, emitter 4), the focus electrode 6and the anode (anode electrode) 9 may be damaged.

In a mechanism in which a discharge takes place in a vacuum space,first, electrons and ions that are emitted from the field emissiondevice under a strong electric field work as a trigger to cause asmall-scaled discharge. And, energy is supplied to the anode electrode 9from the anode-electrode power source (anode-electrode control circuit)10, the anode electrode 9 is locally temperature-increased, and anoccluded gas inside the anode electrode 9 is released, or a materialconstituting the anode electrode 9 is caused to vaporize, so that thesmall-scaled discharge presumably grows to be an abnormal discharge.Besides the anode-electrode power source (anode-electrode controlcircuit) 10, energy accumulated in an electrostatic capacity formedbetween the anode electrode 9 and the field emission device may possiblywork as a source for supplying energy that promotes the growth to theabnormal discharge.

For inhibiting the abnormal discharge (vacuum arc discharge), it iseffective to control the emission of electrons and ions which triggerthe discharge, while it is required to control the particles extremelystrictly therefor. In a general production process of the cathode panelsor the anode panels or the display panels using the anode panels or thecathode panels, practicing the above control involves great technicaldifficulties.

It is therefore an object of the present invention to provide a coldcathode field emission display that is so structured to be capable ofinhibiting the occurrence of critical damage caused by energy, which isgenerated by an electrostatic capacity between the anode electrode andthe field emission device, on an anode electrode or an electrodeconstituting the cold cathode field emission device even when adischarge takes place between the electrode constituting the coldcathode field emission device and the anode electrode.

DISCLOSURE OF THE INVENTION

The cold cathode field emission display according to a first aspect ofthe present invention for achieving the above object is a cold cathodefield emission display comprising a cathode panel having a plurality ofcold cathode field emission devices and an anode panel which panels arebonded to each other in their circumferential portions,

the anode panel comprising a substrate, a phosphor layer formed on thesubstrate, an anode electrode formed on the phosphor layer and aresistance layer for controlling a discharge current, the resistancelayer being formed on the anode electrode and having a thickness oft_(R) (unit: μm), and

the cold cathode field emission display satisfying the followingexpression (1).Q>(½)C·V _(A) ²  (1)

The cold cathode field emission display according to a second aspect ofthe present invention for achieving the above object is a cold cathodefield emission display comprising a cathode panel having a plurality ofcold cathode field emission devices and an anode panel which panels arebonded to each other in their circumferential portions,

the anode panel comprising a substrate, a phosphor layer formed on thesubstrate, an anode electrode formed on the phosphor layer and aresistance layer for controlling a discharge current, the resistancelayer being formed on the anode electrode and having a thickness oft_(R) (unit: μm), and

the cold cathode field emission display satisfying the followingexpression (2).t _(R)×10⁻²>(½)C·V _(A) ²  (2)

The cold cathode field emission display according to the first or secondaspect of the present invention may have a constitution that each coldcathode field emission device comprises:

-   (a) a cathode electrode being formed on the supporting member and    extending in a first direction,-   (b) an insulating layer formed on the supporting member and the    cathode electrode,-   (c) a gate electrode being formed on the insulating layer and    extending in a second direction different from the first direction,-   (d) an insulating film formed on the gate electrode and the    insulating layer,-   (e) a focus electrode formed on the insulating film,-   (f) an opening portion formed through the focus electrode, the    insulating film, the gate electrode and the insulating layer, and-   (g) an electron-emitting portion exposed in a bottom portion of the    opening portion.

In this case, each cold cathode field emission device may have aconstitution further comprising:

-   (h) a second resistance layer for controlling a discharge current,    the second resistance layer being formed on the focus electrode and    having a thickness of t′_(R) (unit: μm). In this case, the cold    cathode field emission display according to the first aspect of the    present invention preferably satisfies    Q′=(½)C′·V _(A) ²  (1′)    and the cold cathode field emission display according to the second    aspect of the present invention preferably satisfies    t′ _(R)×10⁻²>(½)C′·V _(A) ²  (2′).

Alternatively, the cold cathode field emission display according to thefirst or second aspect of the present invention may have a constitutionthat each cold cathode field emission device comprises:

-   (a) a cathode electrode being formed on a supporting member and    extending in a first direction,-   (b) an insulating layer formed on the supporting member and the    cathode electrode,-   (c) a gate electrode being formed on the insulating layer and    extending in a second direction different from the first direction,-   (d) an opening portion formed through the gate electrode and the    insulating layer, and-   (e) an electron-emitting portion exposed in a bottom portion of the    opening portion.

The cold cathode field emission display according to a third aspect ofthe present invention for achieving the above object is a cold cathodefield emission display comprising a cathode panel having a plurality ofcold cathode field emission devices and an anode panel which panels arebonded to each other in their circumferential portions,

the anode panel comprising a substrate, a phosphor layer formed on thesubstrate and an anode electrode formed on the phosphor layer,

each cold cathode field emission device comprising:

-   (A) a cathode electrode being formed on a supporting member and    extending in a first direction,-   (B) an insulating layer formed on the supporting member and the    cathode electrode,-   (C) a gate electrode being formed on the insulating layer and    extending in a second direction different from the first direction,-   (D) an insulating film formed on the gate electrode and the    insulating layer,-   (E) a focus electrode formed on the insulating film,-   (F) a resistance layer for controlling a discharge current, the    resistance layer being formed on the focus electrode and having a    thickness of t_(R) (unit: μm),-   (G) an opening portion formed through the focus electrode, the    insulating film, the gate electrode and the insulating layer, and-   (H) an electron-emitting portion exposed in a bottom portion of the    opening portion, and

the cold cathode field emission display satisfying the followingexpression (3).Q>(½)C·V _(A) ²  (3)

The cold cathode field emission display according to a fourth aspect ofthe present invention for achieving the above object is a cold cathodefield emission display comprising a cathode panel having a plurality ofcold cathode field emission devices and an anode panel which panels arebonded to each other in their circumferential portions,

the anode panel comprising a substrate, a phosphor layer formed on thesubstrate and an anode electrode formed on the phosphor layer,

each cold cathode field emission device comprising:

-   (A) a cathode electrode being formed on a supporting member and    extending in a first direction,-   (B) an insulating layer formed on the supporting member and the    cathode electrode,-   (C) a gate electrode being formed on the insulating layer and    extending in a second direction different from the first direction,-   (D) an insulating film formed on the gate electrode and the    insulating layer,-   (E) a focus electrode formed on the insulating film,-   (F) a resistance layer for controlling a discharge current, the    resistance layer being formed on the focus electrode and having a    thickness of t_(R) (unit: μm),-   (G) an opening portion formed through the focus electrode, the    insulating film, the gate electrode and the insulating layer, and-   (H) an electron-emitting portion exposed in a bottom portion of the    opening portion, and the cold cathode field emission display    satisfying the following expression (4).    t _(R)×10⁻²>(½)C·V _(A) ²  (4)

In the cold cathode field emission display according to the first orthird aspect of the present invention, when a material constituting theresistance layer vaporizes from a solid phase through a liquid phase,the following expression is given.

Q ≈ π ⋅ t_(R) ⋅ r_(R)² ⋅ d_(R) × [C_(m_S)(T_(L) − T_(r)) + Q_(S_L) + C_(m_L)(T_(G) − T_(L)) + Q_(L_G)] × 10⁻⁶

In the cold cathode field emission display according to the first orthird aspect of the present invention, when a material constituting theresistance layer vaporizes from a solid phase directly, the followingexpression is given.Q≈π·t _(R) ·r _(R) ² ·d _(R) ×[C _(m) _(—) _(S)(T _(G) −T _(r))+Q _(L)_(—) _(G)]×10⁻⁶

In the cold cathode field emission display according to any one of thefirst to fourth aspects of the present invention, V_(A) is a voltage (V)to be applied to the anode electrode.

In the expressions (1) to (4), rigorously, V_(A) represents a voltagedifference between a voltage to be applied to the anode electrode and avoltage to be applied to that electrode (for example, a focus electrode)of the cold cathode field emission device which is opposed to the anodeelectrode. Since, however, the voltage to be applied to the anodeelectrode is sufficiently high as compared with the voltage to beapplied to that electrode (for example, a focus electrode) of the coldcathode field emission device which is opposed to the anode electrode,it is determined that V_(A) on the right-hand side of each of theexpressions (1) to (4) is a voltage to be applied to the anodeelectrode.

In the cold cathode field emission display according to the first orsecond aspect of the present invention, “C” represents an electrostaticcapacity (F) between the cold cathode field emission device and theanode electrode. In the cold cathode field emission display according tothe third or fourth aspect of the present invention, “C” represents anelectric capacity (F) between the focus electrode and the anodeelectrode. In a preferred embodiment according to the first aspect ofthe present invention, “C′” represents an electrostatic capacity (F)between the focus electrode and the anode electrode.

In the cold cathode field emission display according to the first orthird aspect of the present invention, further,

-   r_(R): a radius (mm) of a vaporization-allowable region of the    resistance layer,-   d_(R): a density (g·cm⁻³) of a material constituting the resistance    layer,-   C_(m) _(—) _(S): a specific heat (J·g⁻¹·K⁻¹) of a material    constituting the resistance layer in a solid state,-   T_(L): a melting point (° C.) of a material constituting the    resistance layer,-   T_(r): room temperature (° C.),-   Q_(S) _(—) _(L): a heat of solution (J·g⁻¹) of a material    constituting the resistance layer,-   C_(m) _(—) _(L): a specific heat (J·g⁻¹·K⁻¹) of a material    constituting the resistance layer in a liquid state,-   T_(G): a boiling point (° C.) of a material constituting the    resistance layer.

Further, when the material constituting the resistance layer vaporizesfrom a solid phase through a liquid phase,

-   Q_(L) _(—) _(G): a heat of vaporization (J·g⁻¹) of a material    constituting a resistance layer.

When a material constituting the resistance layer vaporizes from a solidphase directly,

-   Q_(L) _(—) _(G): a sum (J·g⁻¹) of a heat of vaporization and a heat    of solution of a material constituting the resistance layer.

In a preferred embodiment according to the first aspect of the presentinvention, when a material constituting the second resistance layervaporizes from a solid phase through a liquid phase, the followingexpression is given.

Q^(′) ≈ π ⋅ t_(R)^(′) ⋅ r_(R)^(′2) ⋅ d_(R)^(′) × [C_(m_S)^(′)(T_(L)^(′) − T_(r)) + Q_(S_L)^(′) + C_(m_L)^(′)(T_(G)^(′) − T_(L)^(′)) + Q_(L_G)^(′)] × 10⁻⁶

Alternatively, in a preferred embodiment according to the first aspectof the present invention, when a material constituting the secondresistance layer vaporizes from a solid phase directly, the followingexpression is given.

Q^(′) ≈ π ⋅ t_(R)^(′) ⋅ r_(R)^(′2) ⋅ d_(R)^(′) × [C_(m_S)^(′)(T_(G)^(′) − T_(r)) + Q_(L_G)^(′)] × 10⁻⁶

In the above expression,

-   r′_(R): a radius (mm) of a vaporization-allowable region of the    second resistance layer,-   d′_(R): a density (g·cm⁻³) of a material constituting the second    resistance layer,-   C′_(m) _(—) _(S): a specific heat (J·g⁻¹·K⁻¹) of a material    constituting the second resistance layer in a solid state,-   T′_(L): a melting point (° C.) of a material constituting the second    resistance layer,-   T_(r): room temperature (° C.),-   Q′_(S) _(—) _(L): a heat of solution (J·g⁻¹) of a material    constituting the second resistance layer,-   C′_(m) _(—) _(L): a specific heat (J·g⁻¹·K⁻¹) of a material    constituting the second resistance layer in a liquid state,-   T′_(G): a boiling point (° C.) of a material constituting the second    resistance layer.

Further, when a material constituting the second resistance layervaporizes from a solid phase through a liquid phase,

-   Q′_(L) _(—) _(G): a heat of vaporization (J·g⁻¹) of a material    constituting the second resistance layer.

When a material constituting the second resistance layer vaporizes froma solid phase directly,

-   Q′_(L) _(—) _(G): a sum (J·g⁻¹) of a heat of solution and a heat of    vaporization of a material constituting the second resistance layer.

The electrostatic capacity “C” between the cold cathode field emissiondevice and the anode electrode can be measured as follows. When the coldcathode field emission device comprises a cathode electrode and a gateelectrode, all of gate electrodes are short-circuited and anelectrostatic capacity between such a short-circuited gate electrode andthe anode electrode is measured by a known method. When the cold cathodefield emission device comprises a cathode electrode, a gate electrodeand a focus electrode, an electrostatic capacity between the focuselectrode and the anode electrode is measured by a known method.

The vaporization-allowable region of the resistance layer or the secondresistance layer does not have any circular form, the radius of a circlehaving the same area as that of the region can be regarded as r_(R) orr′_(R).

In the cold cathode field emission device provided in the the coldcathode field emission display according to any one of the first tofourth aspects of the present invention including the preferredembodiments (these will be sometimes referred to as “the display of thepresent invention” hereinafter), preferably, the cathode electrode andthe gate electrode have the form of a stripe, and the projection imageof the cathode electrode and the projection image of the gate electrodecross each other at right angles in view of the simplification ofstructure of the cold cathode field emission display.

In the display of the present invention, desirably, the focus electrodehas the form of one sheet that covers an effective field (a region tofunction as an actual display portion). An opening portion is formed inthe focus electrode for passing electrons emitted from anelectron-emitting region or an electron-emitting portion through thefocus electrode. The above opening portion may be provided in each coldcathode field emission device, or may be provided in eachelectron-emitting region (each overlap region). The electron-emittingregion is constituted of a single or a plurality of electron-emittingportions, which constitutes the electron emission device, formed in aregion (an overlap region) where a projection image of the cathodeelectrode and a projection image of the gate electrode overlap.

In the display of the present invention, the anode electrode may have aconstitution having the form of one sheet that covers the effectivefield, or may be constituted of a set of N anode electrode units (N≧2).In the latter case, the above “C” represents an electrostatic capacity(unit: F) between the cold cathode field emission device or the focuselectrode and the anode electrode unit. In the anode electrode unit, forexample, when the total number of columns of unit phosphor layers(phosphor layers that generate one bright spot in a display) that arearranged in the form of a straight line and constitute one subpixel isn, there may be employed a constitution in which N=n, there may beemployed another constitution in which n=α·N (α is an integer of 2 ormore, preferably 10≦α≦100, more preferably 20≦α≦50), or the number N maybe a number obtained by adding 1 to the number of spacers (to bedescribed later) provided at regular intervals. The size of each of theanode electrode units may be constant regardless of their positions ormay be different depending upon their positions.

When the distance between the anode electrode unit and the cold cathodefield emission device is “L” (unit: mm) and when the anode electrodeunit has an area S_(AU) (unit: mm²), preferably,(V_(A)/7)²×(S_(AU)/L)≦2250 is satisfied, more preferably,(V_(A)/7)²×(S_(AU)/L)≦450 is satisfied, for preventing the scale-up ofdamage caused on the anode electrode unit, such as melting of the anodeelectrode unit, due to a discharge between the anode electrode unit andthe cold cathode field emission device. When a convexoconcave shapeexists in the anode electrode unit and when the distance “L” between theanode electrode unit and the cold cathode field emission device is notconstant, the shortest distance between the anode electrode unit and thecold cathode field emission device is taken as “L”.

In the display of the present invention, the material for constitutingthe resistance layer includes carbon materials such as silicon carbide(SiC) and SiCN; SiN; refractory metal oxides such as ruthenium oxide(RuO₂), tantalum oxide, tantalum oxide, chromium oxide and titaniumoxide; semiconductor materials such as amorphous silicon; and ITO. Theresistance layer can be formed by a PVD method such as a vapordeposition method and a sputtering method; or a CVD method.

Examples of the cold cathode field emission device (to be abbreviated as“field emission device” hereinafter) include:

-   (1) a Spindt-type field emission device (field emission device in    which a conical electron-emitting portion is formed on the cathode    electrode positioned in the bottom portion of the opening portion),-   (2) a plane-type field emission device (field emission device in    which a nearly plane-surface-shaped electron-emitting portion is    formed on the cathode electrode positioned in the bottom portion of    the opening portion),-   (3) a crown-type field emission device (field emission device in    which a crown-shaped electron-emitting portion is formed on the    cathode electrode positioned in the bottom portion of the opening    portion),-   (4) a flat-type field emission device that emits electrons from the    surface of the flat cathode electrode,-   (5) a crater-type field emission device that emits electrons from    convex portions of surface of the cathode electrode having a    convexoconcave shape formed on the surface, and-   (6) an edge-type field emission device that emits electrons from an    edge portion of the cathode electrode.

In addition to the above-mentioned forms of the field emission device, adevice generally called a surface-conduction-type electron emittingdevice is known as the field emission device and can be applied to thecold cathode field emission display of the present invention. In thesurface-conduction-type electron emitting device, thin films composed ofmaterial such as tin oxide (SnO₂), gold (Au), indium oxide (In₂O₃)/tinoxide (SnO₂), carbon, palladium oxide (PdO) or the like and having avery small area are formed in the form of a matrix on the substratemade, for example, of glass. Each thin film is constituted of a pair ofthin film fragments and has a constitution in which a wiring in the rowdirection is connected to one of each pair of the thin film fragmentsand a wiring in the column direction is connected to the other of eachpair of the thin film fragments and a several nm gap is formed betweenone of each pair of the thin film fragments and the other of each pairof the thin film fragments. In the thin film selected by the wiring inthe row direction and the wiring in the column direction, electrons areemitted from the thin film through the gap.

In the display of the present invention, the substrate for constitutingthe anode panel includes a glass substrate, a glass substrate having aninsulating film formed on its surface, a quartz substrate, a quartzsubstrate having an insulating film formed on its surface and asemiconductor substrate having an insulating film formed on its surface.From the viewpoint that the production cost is decreased, it ispreferred to use a glass substrate or a glass substrate having aninsulating film formed on its surface. Examples of the glass substrateinclude high-distortion glass, soda glass (Na₂O.CaO.SiO₂), borosilicateglass (Na₂O.B₂O₃.SiO₂), forsterite (2MgO.SiO₂) and lead glass(Na₂O.PbO.SiO₂). A supporting member for constituting the cathode panelcan have the same constitution as that of the above substrate.

The material for constituting the cathode electrode, the gate electrodeor the focus electrode includes metals such as aluminum (Al), tungsten(W), niobium (Nb), tantalum (Ta), molybdenum (Mo), chromium (Cr), copper(Cu), gold (Au), silver (Ag), titanium (Ti), nickel (Ni) and the like;alloys or compounds containing these metal elements (for example,nitrides such as TiN and silicides such as WSi₂, MoSi₂, TiSi₂ andTaSi₂); electrically conductive metal oxides such as ITO (indium-tinoxide), indium oxide and zinc oxide; and semiconductors such as silicon(Si). For making or forming the cathode electrode, the gate electrode orthe focus electrode, a thin film made of the above material is formed ona substratum by a known thin film forming method such as a CVD method, asputtering method, a vapor deposition method, an ion-plating method, anelectrolytic plating method, an electroless plating method, a screenprinting method, a laser abrasion method or a sol-gel method. When thethin film is formed on the entire surface of the substratum, the thinfilm is patterned by a known patterning method to form the abovemembers. When a patterned resist is formed on the substratum in advanceof the formation of the thin film, the above members can be formed by alift-off method. Further, when vapor deposition is carried out using amask having openings conforming to the cathode electrode or the gateelectrode, or when screen printing is carried out with a screen havingsuch openings, no patterning is required after the formation of the thinfilm.

As a material for constituting the insulating layer or the insulatingfilm which constitutes the field emission device, SiO₂-containingmaterial such as SiO₂, BPSG, PSG, BSG, AsSG, PbSG, SiN, SiON, spin onglass (SOG), low-melting-point glass and a glass paste; SiN; aninsulating resin such as polyimide and the like can be used alone or incombination. The insulating layer or the insulating film can be formedby a known method such as a CVD method, an application method, asputtering method or a screen printing method.

The electron-emitting portion will be explained in detail later.

Examples of a material for constituting the anode electrode includealuminum (Al) and chromium (Cr). When the anode electrode is made ofaluminum (Al) or chromium (Cr), for example, the specific thickness ofthe anode electrode is 3×10⁻⁸ m (30 nm) to 1.5×10⁻⁷ m (150 nm),preferably 5×10⁻⁸ m (50 nm) to 1×10⁻⁷ m (100 nm). The anode electrodecan be formed by a vapor deposition method or a sputtering method.

The phosphor layer may be made of monochromatic phosphor particles, orit may be made of phosphor particles of three primary colors. Further,the arrangement form of the phosphor layer may be a dot matrix form, orit may be a stripe form. In the arrangement form such as a dot matrixform or a stripe form, a black matrix for improvement in contrast may beembedded in a space between one phosphor layer and another adjacentphosphor layer.

Further, the anode panel is preferably provided with a plurality ofseparation walls for preventing the occurrence of a so-called opticalcrosstalk (color mixing) that is caused when electrons recoiling fromthe phosphor layer or secondary electrons emitted from the phosphorlayer enter another phosphor layer, or for preventing the collision ofelectrons with other phosphor layer when electrons recoiling from thephosphor layer or secondary electrons emitted from the phosphor layerenter other phosphor layer over the separation wall.

The form of the separation walls includes the form of a lattice(grilles), that is, a form in which the separation wall surrounds foursides of the phosphor layer corresponding to one pixel and having a planform of nearly a rectangle (or dot-shaped), and a stripe or band-likeform that extends in parallel with opposite two sides of a rectangularor stripe-shaped phosphor layer. When the separation wall(s) has(have)the form of a lattice, the separation wall may have a form in which theseparation wall continuously or discontinuously surrounds four sides ofone phosphor layer. When the separation wall(s) has(have) the form of astripe or band-like form, the form may be continuous or discontinuous.The formed separation walls may be polished to flatten the top surfaceof each separation wall.

For improving the contrast of display images, preferably, a black matrixthat absorbs light from the phosphor layer is formed between onephosphor layer and another adjacent phosphor layer and between theseparation wall and the substrate. As a material for constituting theblack matrix, it is preferred to select a material that absorbs at least99% of light from the phosphor layer. The above material includescarbon, a thin metal film (made, for example, of chromium, nickel,aluminum, molybdenum and an alloy of these), a metal oxide (for example,chromium oxide), metal nitride (for example, chromium nitride), aheat-resistant organic resin, glass paste, and glass paste containing ablack pigment or electrically conductive particles of silver or thelike. Specific examples thereof include a photosensitive polyimideresin, chromium oxide, and a chromium oxide/chromium stacked film.Concerning the chromium oxide/chromium stacked film, the chromium filmis to be in contact with the substrate.

When the cathode panel and the anode panel are bonded in theircircumferential portions, the bonding may be carried out with anadhesive layer or with a frame made of an insulating rigid material suchas glass or ceramic and an adhesive layer. When the frame and theadhesive layer are used in combination, the facing distance between thecathode panel and the anode panel can be adjusted to be longer byproperly determining the height of the frame than that obtained when theadhesive layer alone is used. While a frit glass is generally used as amaterial for the adhesive layer, a so-called low-melting-point metalmaterial having a melting point of approximately 120 to 400° C. may beused. The low-melting-point metal material includes In (indium; meltingpoint 157° C.); an indium-gold low-melting-point alloy; tin(Sn)-containing high-temperature solders such as Sn₈₀Ag₂₀ (melting point220 to 370° C.) and Sn₉₅Cu₅ (melting point 227 to 370° C.); lead(Pb)-containing high-temperature solders such as Pb_(97.5)Ag_(2.5)(melting point 304° C.), Pb_(94.5)Ag_(5.5) (melting point 304 to 365°C.) and Pb_(97.5)Ag_(1.5)Sn_(1.0) (melting point 309° C.); zinc(Zn)-containing high-temperature solders such as Zn₉₅Al₅ (melting point380° C.); tin-lead-containing standard solders such as Sn₅Pb₉₅ (meltingpoint 300 to 314° C.) and Sn₂Pb₉₈ (melting point 316 to 322° C.); andbrazing materials such as Au₈₈Ga₁₂ (melting point 381° C.) (all of theabove parenthesized values show atomic %).

When three members of the substrate, the supporting member and the frameare bonded, these three members may be bonded at the same time, or oneof the substrate and the supporting member may be bonded to the frame ata first stage, and then the other of the substrate and the supportingmember may be bonded to the frame at a second stage. When bonding of thethree members or bonding at the second stage is carried out in ahigh-vacuum atmosphere, a space surrounded by the substrate, thesupporting member, the frame and the adhesive layer comes to be a vacuumspace upon bonding. Otherwise, after the three members are bonded, thespace surrounded by the substrate, the supporting member, the frame andthe adhesive layer may be vacuumed to obtain a vacuum space. When thevacuuming is carried out after the bonding, the pressure in anatmosphere during the bonding may be any one of atmospheric pressure andreduced pressure, and the gas constituting the atmosphere may be ambientatmosphere or an inert gas containing nitrogen gas or a gas (forexample, Ar gas) coming under the group 0 of the periodic table.

When the vacuuming is carried out after the bonding, the vacuuming canbe carried out through a tip tube pre-connected to the substrate and/orthe supporting member. Typically, the tip tube is made of a glass tubeand is bonded to a circumference of a through-hole formed in anineffective field of the substrate and/or the supporting member (i.e.,the field other than the effective field which works as a displayportion) with a frit glass or the above low-melting-point metalmaterial. After the space reaches a predetermined degree of vacuum, thetip tube is sealed by thermal fusion. It is preferred to heat and thentemperature-decrease the cold cathode field emission display as a wholebefore the sealing, since residual gas can be released into the space,and the residual gas can be removed out of the space by vacuuming.

The display is internally in a high vacuum state, and atmosphericpressure is exerted on the display. The display is therefore preferablyinternally provided with spacers for preventing atmospheric pressurefrom damaging the display. Examples of a material for constituting thespacer include glass and ceramics (for example, a ceramic obtained byadding titanium oxide, chromium oxide, iron oxide, vanadium oxide ornickel oxide to mullite, alumina, barium titanate, lead titanatezirconate, zirconia, cordierite, barium borosilicate, iron silicate or aglass ceramic material). The spacer can be fixed to the anode panel, forexample, with a spacer holder formed in the anode panel or partitionwalls.

In the display of the present invention, the cathode electrode isconnected to a cathode-electrode control circuit, the gate electrode isconnected to a gate-electrode control circuit, the anode electrode isconnected to an anode-electrode control circuit, and the focus electrodeis connected to the focus-electrode control circuit. These controlcircuits can be constituted of known circuits. The output voltage V_(A)of the anode-electrode control circuit is generally constant, and it canbe set, for example, at 5 kilovolts to 10 kilovolts. Concerning thevoltage V_(C) to be applied to the cathode electrode and the voltageV_(G) to be applied to the gate electrode, there can be employed (1) amethod in which the voltage V_(C) to be applied to the cathode electrodeis set at a constant level and the voltage V_(G) to be applied to thegate electrode is changed, (2) a method in which the voltage V_(C) to beapplied to the cathode electrode is changed and the voltage V_(G) to beapplied to the gate electrode is set at a constant level, or (3) amethod in which the voltage V_(C) to be applied to the cathode electrodeis changed and the voltage V_(G) to be applied to the gate electrode isalso changed. A constant voltage of 0 volt or approximately −20 volts atmaximum is applied to the focus electrode from the focus-electrodecontrol circuit.

In the cold cathode field emission display of the present invention, therelationship of the total energy “Q” required for the vaporization ofthe resistance layer, the electrostatic capacity “C” between the coldcathode field emission device or the focus electrode and the anodeelectrode and the voltage V_(A) to be applied to the anode electrode aredefined, so that the occurrence of damage, caused by energy generated onbasis of an electrostatic capacity formed between the anode electrodeand the field emission device, on members constituting the resistancelayer, the anode electrode or the cold cathode field emission device canbe reliably suppressed even when a discharge takes place between thecold cathode field emission device or the focus electrode and the anodeelectrode. Alternatively, the relationship of the thickness t_(R) of theresistance layer, the electrostatic capacity “C” between the coldcathode field emission device or the focus electrode and the anodeelectrode and the voltage V_(A) to be applied to the anode electrode aredefined, so that the occurrence of damage, caused by energy generated onthe basis of an electrostatic capacity formed between the anodeelectrode and the field emission device, on members constituting theresistance layer, the anode electrode and the cold cathode fieldemission device can be reliably suppressed even when a discharge takesplace between the cold cathode field emission device or the focuselectrode and the anode electrode. Further, the resistance layer isprovided, so that the peak value of a discharge current can bedecreased.

Further, when the anode electrode has a form in which the anodeelectrode is divided into the anode electrode units having smaller areasin place of forming the anode electrode on the entire region of theeffective field, the electrostatic capacity between the cold cathodefield emission device or the focus electrode and the anode electrodeunit can be decreased, so that the thickness of the resistance layer canbe consequently decreased. Further, the energy generated on the basis ofthe electrostatic capacity formed between the anode electrode and thefield emission device can be decreased, so that extent of the damagecaused on the anode electrode by a discharge can be further decreased.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic partial end view of a cold cathode field emissiondisplay of Example 1.

FIG. 2 is a schematic partial perspective view obtained when a cathodepanel CP and an anode panel AP constituting the cold cathode fieldemission display of Example 1 are disassembled.

FIG. 3 is a schematic layout drawing that shows a layout of partitionwalls, spacers and phosphor layers in the anode panel constituting acold cathode field emission display.

FIG. 4 is a schematic layout drawing that shows a layout of partitionwalls, spacers and phosphor layers in the anode panel constituting acold cathode field emission display.

FIG. 5 is a schematic layout drawing that shows a layout of partitionwalls, spacers and phosphor layers in the anode panel constituting acold cathode field emission display.

FIG. 6 is a schematic layout drawing that shows a layout of partitionwalls, spacers and phosphor layers in the anode panel constituting acold cathode field emission display.

FIG. 7 is a schematic showing of a discharge state when a resistancelayer is formed in a discharge current path in the cold cathode fieldemission display of Example 1.

FIG. 8 is an equivalent circuit found when a discharge takes placebetween the anode electrode and the focus electrode in the cold cathodefield emission display of Example 1.

FIG. 9 is a graph showing a calculation result with regard to adischarge current when the electric resistance value “R” of a resistancelayer for controlling a discharge current in the equivalent circuitshown in FIG. 8 is set at 0.9Ω.

FIG. 10 is a schematic partial end view of a cold cathode field emissiondisplay of Example 2.

FIG. 11 is a schematic partial end view of a cold cathode field emissiondisplay of Example 3.

FIG. 12 is a schematic plan view of an anode electrode in a cold cathodefield emission display of Example 4.

FIGS. 13A and 13B are a schematic partial end view of an anode paneltaken along line A-A in FIG. 12 and a schematic partial end view of thesame taken along line B-B in FIG. 12, respectively.

FIG. 14 is an equivalent circuit found when a discharge takes placebetween an anode electrode unit and a focus electrode in the coldcathode field emission display of Example 4 having no resistance layer.

FIG. 15 is a graph showing simulation results with regard to a change inabnormal discharge current “i” when the anode electrode unit of the coldcathode field emission display of Example 4 has an area S_(AU) of 9000mm², 3000 mm² and 450 mm².

FIG. 16 is a graph showing simulation results with regard to anintegration value of energy generated during an abnormal discharge whenthe anode electrode unit of the cold cathode field emission display ofExample 4 has an area S_(AU) of 9000 mm², 3000 mm² and 450 mm².

FIGS. 17A and 17B are schematic partial end views of a supportingmember, etc., for explaining a method of manufacturing a Spindt-typecold cathode field emission device.

FIGS. 18A and 18B, following FIG. 17B, are schematic partial end viewsof the supporting member, etc., for explaining a method of manufacturingthe Spindt-type cold cathode field emission device.

FIGS. 19A and 19B are schematic partial cross-sectional views of asupporting member, etc., for explaining a method of manufacturing aplane-type cold cathode field emission device (No. 1).

FIGS. 20A and 20B, following FIG. 19B, are schematic partialcross-sectional views of a supporting member, etc., for explaining themethod of manufacturing the plane-type cold cathode field emissiondevice (No. 1).

FIGS. 21A and 21B are a schematic partial cross-sectional view of aplane-type cold cathode field emission device (No. 2) and a schematicpartial cross-sectional view of a flat-type cold cathode field emissiondevice, respectively.

FIGS. 22A to 22F are schematic partial cross-sectional views of asubstrate, etc., for explaining a method of manufacturing an anodepanel.

FIG. 23 is a schematic partial end view of a variant of the cold cathodefield emission display.

FIG. 24 is a schematic partial end view of another variant of the coldcathode field emission display.

FIG. 25 is a schematic showing of a layout state of a focus electrode,an opening portion formed through the focus electrode and an openingportion formed through the gate electrode in another variant of the coldcathode field emission display shown in FIG. 24, FIG. 25 being drawn byviewing the electron-emitting region from above.

FIG. 26 is a schematic partial end view of a field emission devicedisclosed in FIG. 2 to JP-A-9-90898.

FIG. 27 is an equivalent circuit found when a discharge takes placebetween an anode electrode and a focus electrode when no resistancelayer is formed.

FIG. 28 is a graph showing results with regard to a discharge currentcalculated when R_(A)=100 kΩ in the equivalent circuit shown in FIG. 27.

FIG. 29 is a graph showing results with regard to a discharge currentcalculated when R_(A)=1 kΩ in the equivalent circuit shown in FIG. 27.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be explained hereinafter with reference toExamples by referring to drawings.

EXAMPLE 1

Example 1 is directed to the cold cathode field emission display (to besimply abbreviated as “display” hereinafter) according to the first andsecond aspects of the present invention.

FIG. 1 shows a schematic partial end view of the display of Example 1,and FIG. 2 shows a schematic partial perspective view found when acathode panel CP and an anode panel AP are disassembled. FIG. 1 omitsshowing of spacers, and FIG. 2 omits showing of partition walls, spacersand a resistance layer and also omits showing of a focus electrode andan insulating layer.

In the display of Example 1, a cathode panel CP having a plurality ofcold cathode field emission devices (to be referred to as “fieldemission devices” hereinafter) having a cathode electrode 11, a gateelectrode 13, a focus electrode 15 and an electron-emitting portion 17and an anode panel AP are bonded to each other through a frame 40 intheir circumferential portions.

The anode panel comprises a substrate 30, a phosphor layer 31(red-light-emitting phosphor layer 31R, green-light-emitting phosphorlayer 31G and blue-light-emitting phosphor layer 31B) formed on thesubstrate 30, an anode electrode 35 formed on the phosphor layer 31 anda resistance layer 36 for controlling a discharge current, theresistance layer 36 being formed on the anode electrode 35 and having athickness of t_(R) (unit: μm). The above anode electrode 35 is made ofan aluminum thin film and has the form of one sheet covering aneffective field. Further, the resistance layer 36 is made of ITO havinga thickness t_(R) of 0.2 μm and is formed on the entire area of theanode electrode 35.

A black matrix 32 is formed on the substrate 30 between one phosphorlayer 31 and another phosphor layer 31. A separation wall 33 is formedon the black matrix 32. FIGS. 3 to 6 schematically show examples oflayout of the separation walls 33, spacer 34 and the phosphor layers 31in the anode panel AP. The plan form of the separation wall 33 includesthe form of a lattice (grid form), i.e., a form that surrounds thephosphor layer 31 having the plan form, for example, of a nearlyrectangle and equivalent to one sub pixel (see FIGS. 3 and 4), and aform of a band (stripe form) extending in parallel with facing two sidesof the phosphor layer 31 having a nearly rectangular form (or stripform) (see FIGS. 5 and 6). The phosphor layer 31 may have the form of astripe that extends vertically on FIGS. 3 to 6. Part of the separationwall 33 works as a spacer holding portion for holding the spacer 34.

The field emission device shown in FIG. 1 is a so-called Spindt-typefield emission device having a conical electron-emitting portion. Thisfield emission device comprises:

-   (a) a cathode electrode 11 formed on a supporting member 10 and    extending in a first direction,-   (b) an insulating layer 12 formed on the supporting member 10 and    the cathode electrode 11,-   (c) a gate electrode 13 being formed on the insulating layer 12 and    extending in a second direction different from the first direction,-   (d) an insulating film 14 formed on the gate electrode 13 and the    insulating layer 12,-   (e) a focus electrode 15 formed on the insulating film 14,-   (f) an opening portion 16 formed through the focus electrode 15, the    insulating film 14, the gate electrode 13 and the insulating layer    12 (an opening portion 16A formed through the focus electrode 15 and    the insulating film 14, an opening portion 16B formed through the    gate electrode 13, and an opening portion 16C formed through the    insulating layer 12), and-   (g) an electron-emitting portion 17 formed on the cathode electrode    11 positioned in the bottom portion of the opening portion.

The electron-emitting portion 17 is constituted, specifically, of aconical electron-emitting portion formed on the cathode electrode 11positioned in a bottom portion of the opening portion 16C. Further, thefocus electrode 15 has the form of one sheet covering the effectivefield. The opening portion 16A formed through the focus electrode 15 isprovided for each cold cathode field emission device.

Generally, the cathode electrode 11 and the gate electrode 13 are formedin the form of a stripe each in directions in which the projectionimages of these two electrodes cross each other at right angles.Generally, a plurality of field emission devices are arranged in aregion (corresponding to one pixel, and the region will be called an“overlap region” or an “electron-emitting region” hereinafter) where theprojection images of the above two electrodes overlap. Further,generally, such electron-emitting regions are arranged in the form of atwo-dimensional matrix within the effective field (which works as anactual display portion) of the cathode panel CP.

The space surrounded by the anode panel AP, the cathode panel CP and aframe 40 is a vacuum space. Atmosphere has a pressure on the anode panelAP and the cathode panel CP. The spacer 34 having a height, for example,of about 1 mm is provided between the anode panel AP and the cathodepanel CP for preventing the pressure from destroying the display.

Each picture element (one pixel) is constituted of a group of fieldemission devices formed in the three overlap regions of the cathodeelectrode 11 and the gate electrode 13 on the cathode panel side, andthe phosphor layer 31 (an aggregate of one unit phosphor layer foremitting light in red 31R, one unit phosphor layer for emitting light ingreen 31G and one unit phosphor layer for emitting light in blue 31B)that faces three overlap regions and is on the anode panel side. Suchpixels are arranged in the effective field on the order of, for example,several hundreds thousand to several millions. Further, each pictureelement (one pixel) is constituted of three subpixels, each pixel isconstituted of a group of the field emission devices formed on theoverlap region of the cathode electrode 11 and the gate electrode 13 ofthe cathode panel side and the phosphor layer 31 (an aggregate of oneunit phosphor layer for emitting light in red 31R, one unit phosphorlayer for emitting light in green 31G and one unit phosphor layer foremitting light in blue 31B) of the anode panel side arranged so as toface the group of the field emission devices.

The anode panel AP and the cathode panel CP are arranged such that theelectron-emitting region and the phosphor layer 31 face each other, andthey are bonded to each other in their circumferential portions throughthe frame 40, whereby a display can be manufactured. An ineffectivefield surrounding the effective field and having peripheral circuits forselecting pixels is provided with a through hole (not shown) forvacuuming, and a tip tube (not shown) that is to be sealed after thevacuuming is connected to the through hole. That is, the spacesurrounded by the anode panel AP, the cathode panel CP and the frame 40is a vacuum space.

A relatively negative voltage V_(c) is applied to the cathode electrode11 from the cathode-electrode control circuit 41, a relatively positivevoltage V_(G) is applied to the gate electrode 13 from thegate-electrode control circuit 42, a relatively negative voltage V_(F)is applied to the focus electrode 15 from the focus-electrode controlcircuit 43, and a positive voltage V_(A) higher than that applied to thegate electrode 13 is applied to the anode electrode 35 from theanode-electrode control circuit 44. When display is performed with theabove display, for example, a scanning signal is inputted to the cathodeelectrode 11 from the cathode-electrode control circuit 41, and a videosignal is inputted to the gate electrode 13 from the gate-electrodecontrol circuit 42. Reversely, a video signal may be inputted to thecathode electrode 11 from the cathode-electrode control circuit 41, anda scanning signal may be inputted to the gate electrode 13 from thegate-electrode control circuit 42. Due to an electric field generatedwhen a voltage is applied between the cathode electrode 11 and the gateelectrode 13, electrons are emitted from the electron-emitting portion17 on the basis of a quantum tunnel effect, and the electrons are drawntoward the anode electrode 35 to collide with the phosphor layers 31. Asa result, the phosphor layers 31 are excited, whereby a desired imagecan be obtained. That is, the operation of the display is basicallycontrolled by the voltage applied to the gate electrode 13 and thevoltage applied to the electron-emitting portion 17 through the cathodeelectrode 11.

FIG. 27 shows an equivalent circuit found when a discharge takes placebetween the anode electrode 35 and the focus electrode 15 in aconventional display having no resistance layer 36.

In this Example, a positive voltage V_(A) (10 kV) was applied to theanode electrode 35 from the anode-electrode control circuit 44 through aresistance element R_(A) for preventing an overcurrent and a discharge.Further, a voltage V_(F) (=0 V) was applied to the focus electrode 15from the focus-electrode control circuit 43 through a 1 kΩ resistanceelement R_(F). The above resistance elements R_(A) and R_(F) are placedoutside the display. Further, the electrostatic capacity “C” between thefield emission device (more specifically, the focus electrode 15) andthe anode electrode 35 is 70 pF. Further, the electric resistance valueR_(D) along a discharge current path (specifically, the electricresistance value of the anode electrode 35 made of aluminum and thefocus electrode) is 0.1 Ω. The anode electrode 35 had a size of 130mm×100 mm.

Discharge currents “i” were calculated at an R_(A)=100 kΩ and R_(A)=1kΩ, and FIGS. 28 and 29 show the results. The calculations disregardedinductance components. When FIGS. 28 and 29 are compared, it is seenthat almost no discharge current “i” flows in the resistance elementsR_(A) and R_(F) but that it flows in a closed system constituted of theanode electrode 35, the discharge current path, the focus electrode 15and the electrostatic capacity “C” as shown by an arrow and comes to beextinct.

The relationship of the total energy “Q” required for vaporization ofthe resistance layer 36 for controlling a discharge current, whichresistance layer 36 has a thickness of t_(R) (unit: μm), and the energy(which will be called “discharge energy” and is (½)C·V_(A) ²hereinafter) generated on the basis of the electrostatic capacity “C”formed between the anode electrode and the field emission device, andthe relationship of the resistance layer 36 having a thickness of t_(R)(unit: μm) and the discharge energy (½)C·V_(A) ² will be explainedbelow.

FIG. 7 schematically shows a discharge state found when the resistancelayer 36 for controlling a discharge current is formed in a dischargecurrent path, and FIG. 8 shows an equivalent circuit found when adischarge takes place between the anode electrode 35 and the focuselectrode 15 when the resistance layer 36 is provided as shown in FIG.1.

For example, it can be considered that the display has no criticalproblem caused on its display function so long as a discharge thatoccurs between the anode electrode 35 and the focus electrode 15 doesnot cause the anode electrode 35 made of aluminum to vaporize to such anextent that an area corresponding approximately to one pixel isvaporized. It can be therefore also considered that so long as thedischarge between the anode electrode 35 and the focus electrode 15 doesnot cause the resistance layer 36 to vaporize to such an extent that anarea corresponding to one pixel vaporizes, the display has no criticalproblem caused on its display function.

That is, it can be said that so long as the discharge energy (½)C·V_(A)² [in which “C” is an electrostatic capacity (unit: F) between the fieldemission device and the anode electrode and V_(A) is a voltage (unit: V)applied to the anode electrode 35] does not exceed the total energy “Q”required for vaporization of the resistance layer 36 having an area ofπ×r_(R) ² (unit: mm²) and a thickness of t_(R) (unit: μm), theresistance layer 36 is not damaged. That is, it is sufficient to satisfythe following expression (1).Q>(½)C·V _(A) ²  (1)

When a material constituting the resistance layer 36 vaporizes from asolid phase through a liquid phase, the total energy “Q” required forvaporization of the resistance layer 36 can be expressed by:

Q ≈ π ⋅ t_(R) ⋅ r_(R)² ⋅ d_(R) × [C_(m_S)(T_(L) − T_(r)) + Q_(S_L) + C_(m_L)(T_(G) − T_(L)) + Q_(L_G)] × 10⁻⁶

Alternatively, when a material constituting the resistance layer 36vaporizes from a solid phase directly, it can be expressed by:Q≈π·t _(R) ·r _(R) ² ·d _(R) ×[C _(m) _(—) _(S)(T _(G) −T _(r))+Q _(L)_(—) _(G)]×10⁻⁶

In the above expressions,

-   r_(R): a radius (mm) of a vaporization-allowable region of the    resistance layer, or a radius (mm) of a size (region) that does not    cause a problem on the display function of a display even when the    resistance layer of such a size (region) vaporizes, or a radius (mm)    of that size (region) of the resistance layer which corresponds to 1    subpixel,-   d_(R): a density (g·cm⁻³) of a material constituting the resistance    layer,-   C_(m) _(—) _(S): a specific heat (J·g⁻¹·K⁻¹) of a material    constituting the resistance layer in a solid state,-   T_(L): a melting point (° C.) of a material constituting the    resistance layer,-   T_(r): room temperature (° C.),-   Q_(S) _(—) _(L): a heat of solution (J·g⁻¹) of a material    constituting the resistance layer,-   C_(m) _(—) _(L): a specific heat (J·g⁻¹·K⁻¹) of a material    constituting the resistance layer in a liquid state,-   T_(G): a boiling point (° C.) of a material constituting the    resistance layer.

Further, when the material constituting the resistance layer vaporizesfrom a solid phase through a liquid phase,

-   Q_(L) _(—) _(G): a heat of vaporization (J·g⁻¹) of a material    constituting the resistance layer.

When a material constituting the resistance layer vaporizes from a solidphase directly,

-   Q_(L) _(—) _(G): a sum (J·g⁻¹) of a heat of vaporization and a heat    of solution of a material constituting the resistance layer.

When the resistance layer 36 is made of carbon, carbon vaporizes from asolid phase directly,

-   d_(R): 2.3 (g·cm⁻³)-   C_(m) _(—) _(S): 6 (J·mol⁻¹·K⁻¹)-   T_(r): 30 (° C.)-   T_(G): 3400 (° C.)-   Q_(L) _(—) _(G): 350 (kJ·mol⁻¹).

The total energy “Q” required for vaporization of the resistance layer36 made of carbon is calculated as shown in the following expression(5), in which units of r_(R) and t_(R) are mm and μm, respectively.Q=7.10×10⁻² ×π×r _(R) ² ×t _(R)(J)  (5)

When C=70 pF and when V_(A)=10 kV, the following expression (6) can beobtained from the expressions (1) and (5).π×r _(R) ² ×t _(R)>4.93×10⁻²  (6)

Further, when π×r_(R) ²=0.04 mm² (this area is approximately as large asan area of one subpixel), it is sufficient that the thickness t_(R) ofthe resistance layer 36 should satisfy the following expression (7).t _(R)>1.2(μm)  (7)

Further, when the anode electrode 35 is divided into 10 anode electrodeunits, C=7 pF, so that it is sufficient that the thickness t_(R) of theresistance layer 36 should satisfy t_(R)>0.12 (μm).

Further, π×r_(R) ²=0.04 mm² is substituted in the expression (5), thefollowing expression (8) can be obtained from the expression (1).2.84×10⁻³ ×t _(R)>(½)C·V _(A) ²  (8)

When the resistance layer 36 for controlling a discharge current is madeof ITO, ITO having a relatively high volume resistivity has an SnO₂content close to 100%, so that it can be considered that ITO hasphysical property values almost equivalent to those of SnO₂. Therefore,the following physical property values of SnO₂ are used as substitutesfor the physical property values of ITO. ITO vaporizes from a solidphase through a liquid phase.

-   d_(R): 6.4 (g·cm⁻³)-   C_(m) _(—) _(S): 53 (J·mol⁻¹·K⁻¹)-   T_(L): 1130 (° C.)-   T_(r): 30 (° C.)-   Q_(S) _(—) _(L): 48 (kJ·mol⁻¹)-   C_(m) _(—) _(L): 53 (J·mol⁻¹·K⁻¹)-   T_(G): 1850 (° C.)-   Q_(L) _(—) _(G): 314 (kJ·mol⁻¹)

Therefore, the total energy “Q” required for vaporization of theresistance layer 36 made of ITO is calculated as shown in the followingexpression (9), in which units of r_(R) and t_(R) are mm and μm,respectively.Q=1.94×10⁻² ×π×r _(R) ² ×t _(R)(J)  (9)

When C=70 pF and when V_(A)=10 kV, the following expression (10-1) canbe obtained from the expressions (1) and (9). Further, when the anodeelectrode is divided into ten anode electrode units, and when C=7 pF andV_(A)=10 kV, the following expression (10-2) can be obtained from theexpressions (1) and (9).π×r _(R) ² ×t _(R)>1.8×10⁻¹  (10-1)π×r _(R) ² ×t _(R)>1.8×10⁻²  (10-2)

Further, when π×r_(R) ²=0.04 mm², it is sufficient that the thicknesst_(R) of the resistance layer 36 should satisfy the followingexpressions (11-1) and (11-2) on the basis of the expressions (10-1) and(10-2).t _(R)>4.5(μm)  (11-1)t _(R)>0.45(μm)  (11-2)

Further, when π×r_(R) ²=0.04 mm² is substituted in the expression (9),the following expression (12) can be obtained from the expression (1).7.8×10⁻⁴ ×t _(R)>(½)C·V _(A) ²  (12)

As a result, it is seen that if it is taken into account that thethickness of the resistance layer 36 for controlling a discharge currentvaries, it is sufficient that the thickness t_(R) (unit: μm) of theresistance layer 36 should satisfy the following expression (2) on thebasis of the expressions (8) and (12).t _(R)×10⁻²>(½)C·V _(A) ²  (2)

The expression (2) is not dependent upon the volume resistivity of amaterial constituting the resistance layer 36 for controlling adischarge current but is dependent upon physical property values such asd_(R), C_(m) _(—) _(S), T_(L), Q_(S) _(—) _(L), C_(m) _(—) _(L), T_(G),and Q_(L) _(—) _(G).

When the thickness t_(R) of the resistance layer 36 for controlling adischarge current is defined as shown by the expression (2), theoccurrence of damage on any region having an area of over 0.04 mm² canbe suppressed in the resistance layer 36 even when a discharge takesplace between the anode electrode 35 and the focus electrode 15.Further, damage on the anode electrode 35 can be also suppressed.

For example, it can be considered that the display has no criticalproblem caused on its display function so long as the discharge betweenthe anode electrode 35 and the focus electrode 15 does not cause theanode electrode 35 made of aluminum to vaporize to such an extent that aportion having an area of π×r₀ ²=0.04 mm² (an area correspondingapproximately to an area of 1 subpixel as described already) vaporizes.

The electric resistance value required of the resistance layer 36 forsuppressing the vaporization of the above anode electrode 35 will beexplained below. The explanation can be also applied to the focuselectrode 15.

A discharge current energy E(r₀) generated by a discharge current “i” inthe anode electrode 35 or the focus electrode 15 can be determined bythe following expression.

That is, a discharge current energy ΔE to be generated in a micro regionpositioned at a distance of a radius r from a discharge point as anorigin (radially width Δr) can be represented by the followingexpression (13-1), in which

-   ρ₀: a volume resistivity (Ω·m) of an anode electrode or a focus    electrode, and-   s₀: a thickness of the anode electrode or the focus electrode.

$\begin{matrix}\begin{matrix}{{\Delta\; E} = {\int{{\rho_{0} \cdot \Delta}\;{{r/\left( {2{\pi \cdot r \cdot s_{0}}} \right)} \cdot i^{2}}{\mathbb{d}t}}}} \\{= {\int{i^{2}{{\mathbb{d}t} \cdot {\int{\left\lbrack {\rho_{0} \cdot {1/\left( {2{\pi \cdot r \cdot s_{0}}} \right)}} \right\rbrack{\mathbb{d}r}}}}}}}\end{matrix} & \left( {13\text{-}1} \right)\end{matrix}$

When the radius r is integrated from (D/2) to r₀, the followingexpression (13-2) can be obtained, in which

-   r₀: a radius (μm) of a region in which the anode electrode or the    focus electrode suffers damage due to a discharge, and-   D: a diameter (μm) of a plasma generated by the discharge.    E(r ₀)=ρ₀·(2πs ₀)⁻¹·ln(2r ₀ /D)·∫i ² dt  (13-2)

As described already, it can be considered that the display has nocritical problem caused on its display function so long as the dischargebetween the anode electrode 35 and the focus electrode 15 does not causethe anode electrode 35 made of aluminum to vaporize to such an extentthat a portion having an area of π×r₀ ²=0.04 mm² (an area correspondingapproximately to an area of 1 subpixel) vaporizes.

An energy found when a portion having an area of π×r₀ ²=0.04 mm² isvaporized by a discharge between the anode electrode 35 and the focuselectrode 15 in the anode electrode 35 made of aluminum will becalculated below. The calculation will be based on values shown in thefollowing Table 1. While the thickness of the anode electrode is assumedto be 1 μm (=s₀), the anode electrode frequently has such a thickness inportions other than a portion on the phosphor layer.

TABLE 1 Thickness of anode electrode 1 μm (=s₀) Melting area 0.04 mm²(=π × r₀ ²) Density of aluminum 2.7 g · cm⁻³ Melting point of aluminum660° C. Boiling point of aluminum 2060° C. Specific heat of aluminum0.214 cal · g⁻¹ · K⁻¹ Heat of solution of aluminum 94.6 cal · g⁻¹ Heatof vaporization of aluminum 293 kJ · mol⁻¹ =10850 J · g⁻¹

A mass M_(A1) (unit: gram) of aluminum melted, an energy Q_(MELT) (unit:Joule) required for aluminum reaching its melting point (660° C.) fromroom temperature (30° C.), an energy Q_(Liq) (unit: Joule) required formelting, an energy Q_(Biol) (unit: Joule) required for reaching aboiling point (2060° C.) from the melting point (660° C.), an energyQ_(Evap) required for vaporization and a total energy Q_(Total) requiredfor vaporization are as follows. A specific heat of aluminum in a solidstate is used as a specific heat of aluminum in Q_(Biol) forconvenience.

$\begin{matrix}{M_{Al} = {0.04 \times 10^{- 2} \times 10^{- 4} \times 2.7}} \\{= {1.08 \times 10^{- 7}\mspace{14mu}(g)}}\end{matrix}$ $\begin{matrix}{Q_{MELT} = {0.214 \times 4.2 \times \left( {660 - 30} \right) \times M_{Al}}} \\{= {6.1 \times 10^{- 5}\mspace{14mu}(J)}}\end{matrix}$ $\begin{matrix}{Q_{Liq} = {94.6 \times 4.2 \times M_{Al}}} \\{= {4.3 \times 10^{- 5}\mspace{14mu}(J)}}\end{matrix}$ $\begin{matrix}{Q_{Biol} = {0.214 \times 4.2 \times \left( {2060 - 660} \right) \times M_{Al}}} \\{= {1.36 \times 10^{- 4}\mspace{14mu}(J)}}\end{matrix}$ $\begin{matrix}{Q_{Evap} = {10850 \times M_{Al}}} \\{= {1.17 \times 10^{- 3}\mspace{14mu}(J)}}\end{matrix}$ $\begin{matrix}{Q_{Total} = {Q_{MELT} + Q_{Liq} + Q_{Biol} + Q_{Evap}}} \\{= {1.41 \times 10^{- 3}\mspace{14mu}(J)}}\end{matrix}$

It can be said that no local evaporation of the anode electrode 35 takesplace so long as the integration value of energy generated in the anodeelectrode 35 during a discharge that takes place between the anodeelectrode 35 and the field emission device does not exceed the totalenergy Q_(Total). That is, it can be said that no portion correspondingto 1 subpixel evaporates in the anode electrode 35. When anode electrode35 is made of molybdenum (Mo), the total energy Q_(Total) is 2.7×10⁻³(J).

That is, it can be said that no local evaporation takes place in theanode electrode 35 made of aluminum, having a thickness of s₀=1 μm, solong as the total energy Q_(Total) and E(r₀) satisfy the relationship ofthe following expression (14).E(r ₀)<Q _(Total)=1.41×10⁻³  (14)

When the anode electrode 35 is made of aluminum and has a thickness s₀of 1 μm, ρ=2.7×10⁻⁸ Ω·m, and a plasma generated by discharge has aradius D of several tens μm at the largest, so that the expression (14)can be specifically represented by the expression (15). Further, sinceπ×r₀ ²=0.04 mm², r₀=0.11 mm.∫i ² dt<1.1×10⁻¹  (15)

In the equivalent circuit shown in FIG. 8, a positive voltage V_(A) (10kV) was applied to the anode electrode 35 from the anode-electrodecontrol circuit 44 through a 100 kΩ resistance element R_(A). Further, avoltage V_(F) (=0 V) was applied to the focus electrode 15 from thefocus-electrode control circuit 43 through a 1 kΩ resistance elementR_(F). The resistance elements R_(A) and R_(F) are arranged outside thedisplay. Further, the electrostatic capacity “C” between the fieldemission device (more specifically, the focus electrode 15) and theanode electrode 35 is 70 pF. Further, the electric resistance valueR_(D) along the discharge current path (specifically, the electricresistance value of the anode electrode 35 and the focus electrode 15made of aluminum each) is 0.1 Ω. The anode electrode 35 had a size of130 mm×100 mm.

A discharge current when the electric resistance value “R” of theresistance layer 36 for controlling a discharge current was 0.9 Ω wascalculated, and FIG. 9 shows the results. An integration value of thedischarge current “i” on the left side of the expression (15) can bedetermined on the basis of the graph of FIG. 9.

Integration values ∫i²dt of a discharge current “i” on the left side ofthe expression (15) were similarly obtained when the electric resistancevalues “R” of the resistance layer 36 for controlling a dischargecurrent were set at various values, and the following Table 2 shows theresults.

TABLE 2 R_(D)(Ω) R(Ω) R_(D) + R(Ω) ∫i²dt 0.1 0.26 0.36 1.1 × 10⁻² J 0.10.9 1.0 3.9 × 10⁻³ J 0.1 4.9 5.0 7.2 × 10⁻⁴ J 0.1 99.9 100 3.5 × 10⁻⁵ J

The following expression (16) is determined from the results in Table 2.∫i ² dt=(R _(D) +R)^(−1.023)/260  (16)

It is seen from the expression (16) that the expression (15) obtainedwhen the anode electrode is made of 1 μm thick aluminum is satisfied solong as the value of an electric resistance value (R+R_(D)) exceeds 0.36Ω, that is, so long as the value of electric resistance value “R” of theresistance layer 36 for controlling a discharge current exceeds 0.26 Ω.The above value of electric resistance value “R” of the resistance layer36 for controlling a discharge current can be controlled by selecting amaterial for constituting the resistance layer 36 for controlling adischarge current and its thickness (t_(R)) as required. As the electricresistance value R_(D) (specifically, electric resistance values of theanode electrode made of aluminum and the focus electrode), there can beused a total value of an average electric resistance value between thecentral portion of the anode electrode 35 and a circumferential portionof the anode electrode 35 and an average electric resistance valuebetween the central portion of the focus electrode 15 and acircumferential portion of the focus electrode 15. Further, as anelectric resistance value R of the resistance layer 36 for controlling adischarge current, there can be used an electric resistance valuebetween front and reverse sides of that portion of the resistance layer36 from which a damage-allowable area (for example, an area for 1subpixel) is removed.

When FIG. 9 is compared with FIGS. 28 and 29, it can be seen that thepeak value of a discharge current is sharply decreased by providing theresistance layer 36 for controlling a discharge current. When theresistance layer 36 for controlling a discharge current is provided, thepeak value of a discharge current is decreased to be as small asapproximately 0.1 times, so that the occurrence of damage to a materialconstituting the field emission device and the anode electrode can beconsequently far more reliably suppressed.

EXAMPLE 2

Example 2 is a variant of Example 1. FIG. 10 shows a schematic partialend view of a display of Example 2. A schematic partial perspectiveexploded view of a cathode panel CP and an anode panel AP is basicallyas shown in FIG. 2.

In the display of Example 2, field emission devices formed in thecathode panel CP have a structure that is similar to that of the fieldemission devices explained in Example 1 except that a second resistancelayer 18A is formed on the focus electrode 15 made of 1 μm thickaluminum. The second resistance layer 18A is made of ITO having athickness of t′_(R)=0.2 μm. The focus electrode 15 has the form of onesheet covering the effective field. The opening portion 16A formedthrough the focus electrode 15 is provided for each cold cathode fieldemission device.

In Example 2, further, the following expression (1′) is satisfied, inwhich

-   C′: an electrostatic capacity (F) between the focus electrode and    the anode electrode, and-   V_(A): a voltage (V) applied to the anode electrode.    Q′>(½)C′·V _(A) ²  (1′)

When a material constituting the second resistance layer 18A vaporizesfrom a solid phase through a liquid phase,

Q^(′) ≈ π ⋅ t_(R)^(′) ⋅ r_(R)^(′2) ⋅ d_(R)^(′) × [C_(m_S)^(′)(T_(L)^(′) − T_(r)) + Q_(S_L)^(′) + C_(m_L)^(′)(T_(G)^(′) − T_(L)^(′)) + Q_(L_G)^(′)] × 10⁻⁶

On the other hand, when a material constituting the second resistancelayer vaporizes from a solid phase directly,

Q^(′) ≈ π ⋅ t_(R)^(′) ⋅ r_(R)^(′2) ⋅ d_(R)^(′) × [C_(m_S)^(′)(T_(G)^(′) − T_(r)) + Q_(L_G)^(′)] × 10⁻⁶

In the above expression,

-   r′_(R): a radius (mm) of a vaporization-allowable region of the    second resistance layer, or a radius (mm) of a size (region) that    does not cause a problem on the display function of a display even    when the second resistance layer of such a size (region) vaporizes,    or a radius (mm) of that size (region) of the second resistance    layer which corresponds to 1 subpixel,-   d′_(R): a density (g·cm⁻³) of a material constituting the second    resistance layer,-   C′_(m) _(—) _(S): a specific heat (J·g⁻¹·K⁻¹) of a material    constituting the second resistance layer in a solid state,-   T′_(L): a melting point (° C.) of a material constituting the second    resistance layer,-   T_(r): room temperature (° C.),-   Q′_(S) _(—) _(L): a heat of solution (J·g⁻¹) of a material    constituting the second resistance layer,-   C′_(m) _(—) _(L): a specific heat (J·g⁻¹·K⁻¹) of a material    constituting the second resistance layer in a liquid state, and-   T′_(G): a boiling point (° C.) of a material constituting the second    resistance layer.

Further, when a material constituting the second resistance layervaporizes from a solid phase through a liquid phase,

-   Q′_(L) _(—) _(G): a heat of vaporization (J·g⁻¹) of a material    constituting the second resistance layer.

When a material constituting the second resistance layer vaporizes froma solid phase directly,

-   Q′_(L) _(—) _(G): a sum (J·g⁻¹) of a heat of solution and a heat of    vaporization of a material constituting the second resistance layer.

Alternatively, the following expression (2′) is satisfied.t′ _(R)×10⁻²>(½)C′·V _(A) ²  (2′)

A detailed explanation of the electric resistance R of the secondresistance layer 18A for controlling a discharge current and a detailedexplanation of the expressions (1′) and (2′) are omitted since they arethe same as those of the electric resistance “R” of the resistance layer36 for controlling a discharge current and the expressions (1) and (2)in Example 1.

EXAMPLE 3

Example 3 is directed to the display according to the third and fourthaspects of the present invention.

FIG. 11 shows a schematic partial end view of the display of Example 3.A schematic partial perspective exploded view of a cathode panel CP andan anode panel AP is basically as shown in FIG. 2.

In the display of Example 3, a cathode panel CP having a plurality ofcold cathode field emission devices having a cathode electrode 11, agate electrode 13, a focus electrode 15 and an electron-emitting portion17 and an anode panel AP are also bonded to each other through a frame40 in their circumferential portions.

A detailed explanation of the anode panel will be omitted since theanode panel has a structure similar to that of the anode panel APexplained in Example 1 except for the non-formation of the resistancelayer 36.

Further, a detailed explanation of field emission devices formed in thecathode panel CP will be omitted since they have a structure similar tothat of the field emission device explained in Example 1 except for theformation of a resistance layer 18 formed on the focus electrode 15 madeof 1 μm thick aluminum. The resistance layer 18 is made of ITO having athickness of t_(R)=0.2 μm. Further, the focus electrode 15 has the formof one sheet covering the effective field. An opening portion 16A formedthrough the focus electrode 15 is formed for each cold cathode fieldemission device.

In Example 3, the following expression (3) is satisfied.Q>(½)C·V _(A) ²  (3)

In the above expression,

Q ≈ π ⋅ t_(R) ⋅ r_(R)² ⋅ d_(R) × [C_(m_S)(T_(L) − T_(r)) + Q_(S_L) + C_(m_L)(T_(G) − T_(L)) + Q_(L_G)] × 10⁻⁶where,

-   C: an electrostatic capacity (F) between the focus electrode and the    anode electrode,-   V_(A): a voltage (V) applied to the anode electrode,-   r_(R): a radius (mm) of a vaporization-allowable region of the    resistance layer, or a radius (mm) of a size (region) that does not    cause a problem on the display function of a display even when the    resistance layer of such a size (region) vaporizes, or a radius (mm)    of that size (region) of the resistance layer which corresponds to 1    subpixel,-   d_(R): a density (g·cm⁻³) of a material constituting the resistance    layer,-   C_(m) _(—) _(S): a specific heat (J·g⁻¹·K⁻¹) of a material    constituting the resistance layer in a solid state,-   T_(L): a melting point (° C.) of a material constituting the    resistance layer,-   T_(r): room temperature (° C.),-   Q_(S) _(—) _(L): a heat of solution (J·g⁻¹) of a material    constituting the resistance layer,-   C_(m) _(—) _(L): a specific heat (J·g⁻¹·K⁻¹) of a material    constituting the resistance layer in a liquid state,-   T_(G): a boiling point (° C.) of a material constituting the    resistance layer, and-   Q_(L) _(—) _(G): a heat of vaporization (J·g⁻¹) of a material    constituting the resistance layer.

Alternatively, the following expression (4) is satisfied.t _(R)×10⁻²>(½)C·V _(A) ²  (4)

In the above expression,

-   C: an electrostatic capacity (F) between the focus electrode and the    anode electrode, and-   V_(A): a voltage (V) applied to the anode electrode.

A detailed explanation of the electric resistance value R of theresistance layer 18 for controlling a discharge current and a detailedexplanation of the expressions (3) and (4) are omitted since they aresimilar to explanations of the electric resistance value R of theresistance layer 36 for controlling a discharge current and theexpressions (1) and (2) in Example 1.

EXAMPLE 4

Example 4 is a variant of Examples 1 to 3. In Example 4, an anodeelectrode is constituted of “N” (N≧2) anode electrode units 35A, and theabove “C” is an electrostatic capacity (unit: F) between the fieldemission device (more specifically, the focus electrode 15) and theanode electrode unit 35A.

FIG. 12 shows a schematic plan view of the anode electrode, FIG. 13Ashows a schematic partial end view of an anode panel AP taken along lineA-A in FIG. 12, and FIG. 13B shows a schematic partial end view of theanode panel AP taken alone line B-B in FIG. 12. FIGS. 12 and 13 omitshowing of a resistance layer 36.

The anode electrode as a whole has a form covering the rectangleeffective field (size: 70 mm×110 mm) and is made of an aluminum thinfilm. The anode electrode in Example 4 is constituted of 200 anodeelectrode units 35A. The relationship of a total number “n” of columnsof unit phosphor layers 31 arranged in the form of a straight line and“N” is n=20N.

The anode electrode unit 35A is large to such an extent that the anodeelectrode unit 35A is not vaporized by an energy (to be referred to as“generation energy” hereinafter) generated on the basis of anelectrostatic capacity C formed between the anode electrode unit 35A andthe field emission device (more specifically, the focus electrode 15)(more specifically, the size being large to such an extent that noportion corresponding to 1 subpixel in the anode electrode unit 35A isvaporized by the above generation energy). Specifically, each anodeelectrode unit 35A had a rectangular outer form and had a size (areaS_(AU)) of 0.33 mm×110 mm. For simplification of drawings, FIG. 12 showsfour anode electrode units 35A.

Each of the “N” anode electrode units 35A is connected to theanode-electrode control circuit 44 through one electric supply line 50.The electric supply line 50 is also made, for example, of an aluminumthin film. A resistance element R_(A) (electric resistance value of 100kΩ in a shown embodiment) is placed between the anode-electrode controlcircuit 44 and the electric supply line 50. The above resistance elementR_(A) is arranged outside the display. A gap 51 is provided between eachanode electrode unit 35A and the electric supply line 50, and each anodeelectrode unit 35A and the electric supply line 50 are connected througha resistance element 52. The resistance element 52 was constituted of aresistance thin film made of amorphous silicon. The resistance element52 is formed on the gap 51 so as to bridge between each anode electrodeunit 35A and the electric supply line 50. The resistance element 52 hasan electric resistance value (r₁) of approximately 30 kΩ.

In the display in Example 4, when the distance between the anodeelectrode unit 35A and the focus electrode 15 is “L” (unit: mm) and whenthe area of the anode electrode unit 35A is S_(AU) (unit: mm²),(V_(A)/7)²×(S_(AU)/L)≦2250 is satisfied, and further,(V_(A)/7)²×(S_(AU)/L)≦450 is satisfied. Specifically, the value of “L”is 1.0 mm, and the value of S_(AU) is 36.3 mm².

Since the anode electrode unit 35A is formed on the substrate 30, on theseparation wall 33 and on the phosphor layer 31, the anode electrodeunit 35A has the form of convexoconcave, and the distance “L” betweenthe anode electrode unit 35A and the field emission device is notconstant. Therefore, the shortest distance between the anode electrodeunit and the field emission device, that is, the distance specificallybetween the anode electrode unit 35A on the separation wall 33 and thefield emission device (more specifically, the gate electrode 15) istaken as “L”.

FIG. 14 shows an equivalent circuit found when a discharge takes placebetween an anode electrode unit 35A and the focus electrode 15 when noresistance layers 18 and 36 are provided. FIG. 14 shows three anodeelectrode units. Due to the discharge between the anode electrode unit35A and the focus electrode 15, a current “i” flows, and the total valueR_(D) of electric resistance values of the anode electrode unit 35A andthe focus electrode 15 was determined to be 0.2 Ω. Further, the valuesof the electrostatic capacity “C” formed by the anode electrode unit 35Aand the focus electrode 15 when the values of S_(AU) were 9000 mm², 3000mm² and 450 mm² were 60 pF, 20 pF and 3 pF, respectively. Further, V_(A)was set at 7 kV. FIGS. 15 and 16 show a change in the current “I”flowing in the anode electrode unit 35A and generation energy in theanode electrode unit 35A when the values of S_(AU) were 9000 mm², 3000mm² and 450 mm². In FIGS. 15 and 16, a curve “A” shows a value when thevalue of S_(AU) was 9000 mm², a curve “B” shows a value when the valueof S_(AU) was 3000 mm², and a curve “C” shows a value when the value ofS_(AU) was 450 mm². Further, an integration value of the generationenergy (integrated value for 1 nanosecond from the occurrence of adischarge) was as shown in the following Table 3. There was carried outa simulation in which the value of the electrostatic capacity “C” formedby the anode electrode unit 35A and the focus electrode 15 at an S_(AU)value of 2250 mm² was 15 pF, and V_(A) was 7 kV, and the following Table3 further shows an integration value of generation energy in thesimulation.

TABLE 3 Integration value of generation energy in Anode electrode unitarea discharge 9000 mm² 5.6 × 10⁻³ (J) 3000 mm² 1.9 × 10⁻³ (J) 2250 mm²1.4 × 10⁻³ (J)  450 mm² 2.8 × 10⁻⁴ (J)

When the anode electrode unit 35A had areas S_(AU) of 9000 mm² and 3000mm², the integration values of generation energy during the dischargebetween the anode electrode unit 35A and the field emission deviceexceed Q_(Total) (1.41×10⁻³ J) explained in Example 1. On the otherhand, when the anode electrode unit 35A has an area of 2250 mm² or less,the integration values of generation energy during the discharge betweenthe anode electrode unit 35A and the field emission device do not at allexceed Q_(Total). There is therefore no case in which the anodeelectrode unit 35A is damaged locally (more specifically, up to a sizecorresponding to 1 subpixel) by the generation energy during thedischarge between the anode electrode unit 35A and the field emissiondevice. Specifically, there is no case in which the anode electrode unit35A is vaporized locally (more specifically, up to a size correspondingto 1 subpixel) by the discharge between the anode electrode unit 35A andthe field emission device.

Generally, energy accumulated in a capacitor having a capacity “c” isrepresented by (½)cV². When a counterpart electrode to the capacitor hasan area “S” and when the distance between the electrodes is “L”, thecapacity “c” of the capacitor is represented by ε(S/L). Therefore, ifthe following expression is satisfied when the counterpart electrode hasan area S_(AU) and when the distance between the anode electrode unit35A and the field emission device is “L”, it follows that the anodeelectrode unit 35A corresponding to the counterpart electrode to thecapacity is not damaged locally (more specifically, up to a sizecorresponding to 1 subpixel).ε(½)(S _(AU) /L)V _(A) ²≦ε(½)[2250/1]7²

When the above expression is modified,(V _(A)/7)²×(S _(AU) /L)≦2250is obtained.(In Re Various Field Emission Devices)

While various field emission devices and methods of manufacturing themwill be explained below, explanations with regard to the formation of aresistance layer 18 on a focus electrode 15 will be omitted. Forexample, after field emission devices are fabricated, the resistancelayer 18 can be formed, for example, by an oblique sputtering method.

While the Spindt-type (field emission devices each having a conicalelectron-emitting portion formed on the cathode electrode 11 positionedin the bottom portion of the opening portion 16) has been explained asfield emission devices in Examples, there may be employed, for example,a plane-type (field emission devices each having a more or lessplane-surfaced electron-emitting portion formed on the cathode electrode11 positioned in the bottom portion of the opening portion 16). Thesefield emission devices will be referred to as field emission deviceseach having a first structure.

Alternatively, there may be employed a field emission device comprising:

-   (a) a stripe-shaped cathode electrode being formed on a supporting    member and extending in a first direction,-   (b) an insulating layer formed on the supporting member and the    cathode electrode,-   (c) a stripe-shaped gate electrode being formed on the insulating    layer and extending in a second direction different from the first    direction,-   (d) an insulating film formed on the gate electrode and the    insulating film,-   (e) a focus electrode formed on the insulating film, and-   (f) an opening portion formed through the focus electrode and the    insulating film and the gate electrode and the insulating layer, and

having a structure in which that portion of the cathode electrode whichis exposed in the bottom portion of the opening portion corresponds toan electron-emitting portion and electrons are emitted from the exposedportion of the cathode electrode in the bottom portion of the openingportion.

The thus-structured field emission device includes a flat-type fieldemission device that emits electrons from a flat surface of the cathodeelectrode. This field emission device will be called a field emissiondevice having a second structure.

In the Spindt-type field emission device, the material for constitutingan electron-emitting portion may include at least one material selectedfrom the group consisting of tungsten, a tungsten alloy, molybdenum, amolybdenum alloy, titanium, a titanium alloy, niobium, a niobium alloy,tantalum, a tantalum alloy, chromium, a chromium alloy andimpurity-containing silicon (polysilicon or amorphous silicon). Theelectron-emitting portion of the Spindt-type field emission device canbe formed by, for example, a vapor deposition method, a sputteringmethod and a CVD method.

In the plane-type field emission device, preferably, theelectron-emitting portion is made of a material having a smaller workfunction Φ than a material for constituting a cathode electrode. Thematerial for constituting an electron-emitting portion can be selectedon the basis of the work function of a material for constituting acathode electrode, a potential difference between the gate electrode andthe cathode electrode, a required current density of emitted electrons,and the like. Typical examples of the material for constituting acathode electrode of the field emission device include tungsten (Φ=4.55eV), niobium (Φ=4.02-4.87 eV), molybdenum (Φ=4.53-4.95 eV), aluminum(Φ=4.28 eV), copper (Φ=4.6 eV), tantalum (Φ=4.3 eV), chromium (Φ=4.5 eV)and silicon (Φ=4.9 eV). The material for constituting anelectron-emitting portion preferably has a smaller work function Φ thanthese materials, and the value of the work function thereof ispreferably approximately 3 eV or smaller. Examples of such a materialinclude carbon (Φ<1 eV), cesium (Φ=2.14 eV), LaB₆ (Φ=2.66-2.76 eV), BaO(Φ=1.6-2.7 eV), SrO (Φ=1.25-1.6 eV), Y₂O₃ (Φ=2.0 eV), CaO (Φ=1.6-1.86eV), BaS (Φ=2.05 eV), TiN (Φ=2.92 eV) and ZrN (Φ=2.92 eV). Morepreferably, the electron-emitting portion is made of a material having awork function Φ of 2 eV or smaller. The material for constituting anelectron-emitting portion is not necessarily required to have electricconductivity.

Otherwise, in the plane-type field emission device, the material forconstituting an electron-emitting portion can be selected from materialshaving a secondary electron gain δ greater than the secondary electrongain δ of the electrically conductive material for constituting acathode electrode. That is, the above material can be properly selectedfrom metals such as silver (Ag), aluminum (Al), gold (Au), cobalt (Co),copper (Cu), molybdenum (Mo), niobium (Nb), nickel (Ni), platinum (Pt),tantalum (Ta), tungsten (W) and zirconium (Zr); semiconductors such assilicon (Si) and germanium (Ge); inorganic simple substances such ascarbon and diamond; and compounds such as aluminum oxide (Al₂O₃), bariumoxide (BaO), beryllium oxide (BeO), calcium oxide (CaO), magnesium oxide(MgO), tin oxide (SnO₂), barium fluoride (BaF₂) and calcium fluoride(CaF₂). The material for constituting an electron-emitting portion isnot necessarily required to have electric conductivity.

In the plane-type field emission device, as a material for constitutingan electron-emitting portion, particularly, carbon is preferred. Morespecifically, diamond, graphite and a carbon-nanotube structure arepreferred. When the electron-emitting portion is made of diamond,graphite or the carbon-nanotube structure, an emitted-electron currentdensity necessary for the display can be obtained at an electric fieldintensity of 5×10⁷ V/m or lower. Further, since diamond is an electricresister, emitted-electron currents obtained from the electron-emittingportions can be brought into uniform currents, and the fluctuation ofbrightness can be suppressed when such field emission devices areincorporated into the display. Further, since the above materialsexhibit remarkably high durability against sputtering by ions ofresidual gas in the display, field emission devices having a longerlifetime can be attained.

Specifically, the carbon-nanotube structure includes a carbon-nanotubeand/or a carbon-nanofiber. More specifically, the electron-emittingportion may be constituted of a carbon-nanotube, it may be constitutedof a carbon-nanofiber, or it may be constituted of a mixture of acarbon-nanotube with a carbon-nanofiber. Macroscopically, thecarbon-nanotube and carbon-nanofiber may have the form of a powder or athin film. The carbon-nanotube structure may have the form of a cone insome cases. The carbon-nanotube and carbon-nanofiber can be produced orformed by a known PVD method as an arc discharge method and a laserabrasion method; and any one of various CVD methods such as a plasma CVDmethod, a laser CVD method, a thermal CVD method, a gaseous phasesynthetic method and a gaseous phase growth method.

The plane-type field emission device can be produced by a method inwhich a dispersion of a carbon-nanotube structure in a binder materialis, for example, applied onto a desired region of the cathode electrodeand the binder material is fired or cured (more specifically, a methodin which the carbon-nanotube structure is dispersed in an organic bindermaterial such as an epoxy resin or an acrylic resin or an inorganicbinder material such as water glass or silver paste and the like, thedispersion is, for example, applied onto a desired region of the cathodeelectrode, then, the solvent is removed and the binder material is firedand cured). The above method will be referred to as “first formingmethod of a carbon-nanotube structure”. The application method includes,for example, a screen printing method.

Alternatively, the plane-type field emission device can be produced by amethod in which a dispersion of the carbon-nanotube structure in a metalcompound solution is applied onto the cathode electrode and then, themetal compound is fired, whereby the carbon-nanotube structure is fixedto the surface of the cathode electrode with a matrix containing metalatoms derived from the metal compound. The above method will be referredto as “second forming method of a carbon-nanotube structure”. The matrixis preferably made of an electrically conductive metal oxide. Morespecifically, it is preferably made of tin oxide, indium oxide,indium-tin oxide, zinc oxide, antimony oxide or antimony-tin oxide.After the firing, there can be obtained a state where part of eachcarbon-nanotube structure is embedded in the matrix, or there can beobtained a state where the entire portion of each carbon-nanotubestructure is embedded in the matrix. The matrix preferably has a volumeresistivity of 1×10⁻⁹ Ω·m to 5×10⁻⁶ Ω·m.

The metal compound for constituting the metal compound solutionincludes, for example, an organometal compound, an organic acid metalcompound and metal salts (for example, chloride, nitrate and acetate).The organic acid metal compound solution is, for example, a solutionprepared by dissolving an organic tin compound, an organic indiumcompound, an organic zinc compound or an organic antimony compound in anacid (for example, hydrochloric acid, nitric acid or sulfuric acid) anddiluting the resultant solution with an organic solvent (for example,toluene, butyl acetate or isopropyl alcohol). Further, the organic metalcompound solution is, for example, a solution prepared by dissolving anorganic tin compound, an organic indium compound, an organic zinccompound or an organic antimony compound in an organic solvent (forexample, toluene, butyl acetate or isopropyl alcohol). When the amountof the solution is 100 parts by weight, the solution preferably has acomposition containing 0.001 to 20 parts by weight of thecarbon-nanotube structure and 0.1 to 10 parts by weight of the metalcompound. The solution may contain a dispersing agent and a surfactant.From the viewpoint of increasing the thickness of the matrix, anadditive such as carbon black or the like may be added to the metalcompound solution. In some cases, the organic solvent may be replacedwith water.

The method for applying onto the cathode electrode the metal compoundsolution in which the carbon-nanotube structure is dispersed includes aspray method, a spin coating method, a dipping method, a die quartermethod and a screen printing method. Of these, a spray method ispreferred in view of easiness in application.

There may be employed a constitution in which the metal compoundsolution in which the carbon-nanotube structure is disperse is appliedonto the cathode electrode, the metal compound solution is dried to forma metal compound layer, then, an unnecessary portion of the metalcompound layer on the cathode electrode is removed, and then the metalcompound is fired. Otherwise, an unnecessary portion of the metalcompound layer on the cathode electrode may be removed after the metalcompound is fired. Otherwise, the metal compound solution may be appliedonly onto a desired region of the cathode electrode.

The temperature for firing the metal compound is preferably, forexample, a temperature at which the metal salt is oxidized to form ametal oxide having electric conductivity, or a temperature at which theorganometal compound or an organic acid metal compound is decomposed toform a matrix (for example, a metal oxide having electric conductivity)containing metal atoms derived from the organometal compound or theorganic acid metal compound. For example, the above temperature ispreferably at least 300° C. The upper limit of the firing temperaturecan be a temperature at which elements constituting the field emissiondevice or the cathode panel do not suffer any thermal damage and thelike.

In the first forming method or the second forming method of acarbon-nanotube structure, it is preferred to carry out a kind of anactivation treatment (washing treatment) of the surface of theelectron-emitting portion after the formation of the electron-emittingportion, since the efficiency of emission of electrons from theelectron-emitting portion is further improved. The above activationtreatment includes a plasma treatment in an atmosphere containing a gassuch as hydrogen gas, ammonia gas, helium gas, argon gas, neon gas,methane gas, ethylene gas, acetylene gas or nitrogen gas.

In the first forming method or the second forming method of acarbon-nanotube structure, the electron-emitting portion may be formedin that portion of the cathode electrode which portion is positioned inthe bottom portion of the opening portion, or the electron-emittingportion may be also formed so as to extend from that portion of thecathode electrode which portion is positioned in the bottom portion ofthe opening portion to the surface of that portion of the cathodeelectrode which portion is different from the portion of the cathodeelectrode in the bottom portion of the opening portion. Further, theelectron-emitting portion may be formed on the entire surface or part ofthe surface of that portion of the cathode electrode which portion ispositioned in the bottom portion of the opening portion.

In the field emission device having the first or second structure,depending upon the structure of field emission device, oneelectron-emitting portion may exist in one opening portion formed in thegate electrode and the insulating layer, or a plurality ofelectron-emitting portions may exist in one opening portion formed inthe gate electrode and the insulating layer, or one electron-emittingportion or a plurality of electron-emitting portions may exist in aplurality of first opening portions formed in the gate electrode and onesecond opening portion which is formed in the insulating layer andcommunicates with such first opening portions.

The plan form of the opening portion formed in the gate electrode andthe insulating layer (form obtained by cutting the opening portion withan imaginary plane in parallel with the surface of the supportingmember) may be any form such as a circle, an oval, a rectangle, apolygon, a rounded rectangle or a rounded polygon. The opening portionformed in the gate electrode can be formed, for example, by isotropicetching, anisotropic etching or by a combination of anisotropic etchingand isotropic etching. Otherwise, the opening portion in the gateelectrode can be formed directly according to the forming method of thegate electrode. The opening portion in the insulating layer can be alsoformed, for example, by isotropic etching, anisotropic etching or by acombination of anisotropic etching and isotropic etching. The openingportion provided in the focus electrode is formed in each cold cathodefield emission device or in each electron-emitting region (each overlapregion).

In the field emission device having the first structure, the resistancelayer may be formed between the cathode electrode and theelectron-emitting portion. Otherwise, when the surface of the cathodeelectrode corresponds to the electron-emitting portion (that is, in thefield emission device having the second structure), the cathodeelectrode may have a three-layered structure constituted of anelectrically conductive material layer, a resistance layer and anelectron-emitting layer corresponding to the electron-emitting portion.The resistance layer can stabilize performances of the field emissiondevice and can attain uniform electron emitting properties. The materialfor constituting a resistance layer includes carbon-containing materialssuch as silicon carbide (SiC) and SiCN; SiN; semiconductor materialssuch as amorphous silicon and the like; and refractory metal oxides suchas ruthenium oxide (RuO₂), tantalum oxide and tantalum nitride. Theresistance layer can be formed by a sputtering method, a CVD method or ascreen-printing method. The resistance value of the resistance layer isapproximately 1×10⁵ to 1×10⁷ Ω, preferably several MΩ.

[Spindt-type Field Emission Device]

As explained in above, basically, the Spindt-type field emission devicecomprises:

-   (a) a stripe-shaped cathode electrode 11 being formed on a    supporting member 10 and extending in a first direction,-   (b) an insulating layer 12 formed on the supporting member 10 and    the cathode electrode 11,-   (c) a stripe-shaped gate electrode 13 being formed on the insulating    layer 12 and extending in a second direction different from the    first direction,-   (d) an insulating film 14 formed on the gate electrode 13 and the    insulating layer 12,-   (e) a focus electrode 15 formed on the insulating layer 14,-   (f) an opening portion 16 formed through the focus electrode 15 and    the insulating film 14 and the gate electrode 13 and the insulating    layer 12 (an opening portion 16A formed through the focus electrode    15 and the insulating film 14, an opening portion 16B formed through    the gate electrode 13, and an opening portion 16C formed through the    insulating layer 12), and-   (g) an electron-emitting portion 17 formed on a cathode electrode 11    positioned in the bottom portion of the opening portion 16, and

has a structure in which electrons are emitted from the conicalelectron-emitting portion 17 exposed in the bottom portion of theopening portion 16.

The method of manufacturing the Spindt-type field emission device willbe explained below with reference to FIGS. 17A, 17B, 18A and 18B whichare schematic partial end views of the supporting member 10, etc.,constituting a cathode panel.

The above Spindt-type field emission device can be obtained basically bya method in which the conical electron-emitting portion 17 is formed byvertical vapor deposition of a metal material. That is, while depositionparticles perpendicularly enter the opening portion 16A formed throughthe focus electrode 15, the amount of deposition particles reaching thebottom portion of the opening portion 16 is gradually decreased byutilizing a masking effect produced by an overhanging deposit formedaround the edge of opening of the opening portion 16A, and theelectron-emitting portion 17, which is a conical deposit, is formed in aself-alignment manner. There will be explained below a method in which apeeling-off layer 19A is formed on the focus electrode 15 beforehand formaking it easy to remove an unnecessary overhanging deposit. In thedrawings for explaining the method of manufacturing a field emissiondevice, one electron-emitting portion alone is shown.

[Step-A0]

A conductive material layer composed, for example, of polysilicon for acathode electrode is formed on a supporting member 10 made, for example,of a glass substrate by a plasma-enhanced CVD method. Then, theconductive material layer for a cathode electrode is patterned by alithograph method and a dry etching method, to form the cathodeelectrode 11 having a stripe form. Thereafter, the insulating layer 12composed of SiO₂ is formed on the entire surface by a CVD method.

[Step-A1]

Then, the conductive material layer (for example, TiN layer) for a gateelectrode is formed on the insulating layer 12 by a sputtering method.Then, the conductive material layer for a gate electrode is patterned bya lithograph method and a dry etching method, to form the stripe-shapedgate electrode 13. The cathode electrode 11 in the form of a stripeextends in a direction rightward and leftward to the paper surface ofthe drawing and the gate electrode 13 in the form of a stripe extends ina direction perpendicular to the paper surface of the drawing.

The gate electrode 13 can be formed by a known thin film forming methodsuch as a PVD method including a vapor deposition method and the like, aCVD method, a plating method including an electroplating method and anelectroless plating method, a screen printing method, a laser abrasionmethod, a sol-gel method, a lift-off method and the like, or acombination of one of them with an etching method as required. Forexample, a stripe-shaped gate electrode can be directly formed when ascreen-printing method or a plating method is employed.

[Step-A2]

Then, an insulating film 14 is formed on the entire surface, and, afocus electrode 15 is formed on the insulating film 14.

[Step-A3]

Then, a resist layer is formed again, and the opening portion 16A isformed through the focus electrode 15 and the insulating film 14 byetching, and further, an opening portion 16B is formed through the gateelectrode 13, and an opening portion 16C is formed through theinsulating layer. The cathode electrode 11 is exposed in the bottomportion of the opening portion 16C, and then, the resist layer isremoved. In the above manner, a structure shown in FIG. 17A can beobtained.

[Step-A4]

As shown in FIG. 17B, a peeling-off layer 19A is then formed on thefocus electrode 15 by oblique vapor deposition of nickel (Ni) while thesupporting member 10 is turned. In this case, the incidence angle ofvaporized particles relative to the normal of the supporting member 10is set at a sufficiently large angle (for example, an incidence angle of65° to 85°), whereby the peeling-off layer 19A can be formed on thefocus electrode 15 almost without depositing any nickel in the bottomportion of the opening portion 16C. The peeling-off layer 19A extendsfrom the opening edge portion of the opening portion 16A like eaves,whereby the diameter of the opening portion 16A is substantiallydecreased.

[Step-A5]

Then, an electrically conductive material such as molybdenum (Mo) isdeposited on the entire surface by vertical vapor deposition (incidenceangle 3° to 10°). During the above vapor deposition, as shown in FIG.18A, as the conductive material layer 19B having an overhanging formgrows on the peeling-off layer 19A, the substantial diameter of theopening portion 16A is gradually decreased, and the vaporized particleswhich contribute to the deposition in the bottom portion of the openingportion 16C gradually come to be limited to particles which pass thecentral region of the opening portion 16C. As a result, acircular-cone-shaped deposit is formed on the bottom portion of theopening portion 16C, and the circular-cone-shaped deposit constitutesthe electron-emitting portion 17.

[Step-A6]

Then, the peeling-off layer 19A is peeled off from the surfaces of thefocus electrode 15 by a lift-off method, and the conductive materiallayer 19B above the focus electrode 15 are selectively removed. Then,the side wall surface of the opening portion 16C formed through theinsulating layer 12 are allowed to recede by isotropic etching, which ispreferred from the viewpoint of exposing the opening end portion of thegate electrode 13. The isotropic etching can be carried out by dryetching using radicals as main etching species like chemical dryetching, or by wet etching using an etching solution. As an etchingsolution, for example, a mixture containing a 49% hydrofluoric acidaqueous solution and pure water in a hydrofluoric acid aqueous solution:pure water volume ratio of 1:100 can be used. Whereby, a field emissiondevice shown in FIG. 18B is completed.

[Plane-type Field Emission Device (No. 1)]

The plane-type field emission device comprises:

-   (a) cathode electrode 11 being formed on a supporting member 10 and    extending in first direction,-   (b) an insulating layer 12 formed on the supporting member 10 and    the cathode electrode 11,-   (c) a gate electrode 13 being formed on the insulating layer 12 and    extending in a second direction different from the first direction,-   (d) an insulating film 14 formed on the gate electrode 13 and the    insulating layer 12,-   (e) a focus electrode 15 formed on the insulating film 14,-   (f) an opening portion 16 formed through the focus electrode 15 and    the insulating film 14 and the gate electrode 13 and the insulating    layer 12 (an opening portion 16A formed through the focus electrode    15 and the insulating film 14, an opening portion 16B formed through    the gate electrode 13, and an opening portion 16C formed through the    insulating layer 12), and-   (g) an electron-emitting portion 17A formed on a cathode electrode    11 positioned in the bottom portion of the opening portion 16, and

has a structure in which electrons are emitted from theelectron-emitting portion 17A exposed in the bottom portion of theopening portion 16.

An electron-emitting portion 17A comprises a matrix 20 and acarbon-nanotube structure (specifically, a carbon-nanotube 21) embeddedin the matrix 20 in a state where the toportion of the carbon-nanotubestructure is projected, and the matrix 20 is made of an electricallyconductive metal oxide (specifically, indium-tin oxide, ITO).

The production method of the field emission device will be explainedwith reference to FIGS. 19A, 19B, 20A and 20B, hereinafter.

[Step-B0]

First, a stripe-shaped cathode electrode 11 made of an approximately 0.2μm thick chromium (Cr) layer is formed on a supporting member 10 made,for example, of a glass substrate, for example, by a sputtering methodand an etching technique.

[Step-B1]

Then, a metal compound solution consisting of an organic acid metalcompound solution in which the carbon-nanotube structure is dispersed isapplied onto the cathode electrode 11, for example, by a spray method.Specifically, a metal compound solution shown in Table 4 is used. In themetal compound solution, the organic tin compound and the organic indiumcompound are in a state where they are dissolved in an acid (forexample, hydrochloric acid, nitric acid or sulfuric acid). Thecarbon-nanotube is produced by an arc discharge method and has anaverage diameter of 30 nm and an average length of 1 μm. In theapplication, the supporting member 10 is heated to 70-150° C.Atmospheric atmosphere is employed as an application atmosphere. Afterthe application, the supporting member 10 is heated for 5 to 30 minutesto fully evaporate butyl acetate off. When the supporting member 10 isheated during the application as described above, the applied solutionbegins to dry before the carbon-nanotube is self-leveled toward thehorizontal direction of the surface of the cathode electrode 11. As aresult, the carbon-nanotube can be arranged on the surface of thecathode electrode 11 in a state where the carbon-nanotube is not in alevel position. That is, the carbon-nanotube can be aligned in thedirection in which the toportion of the carbon-nanotube faces the anodeelectrode, in other words, the carbon-nanotube comes close to the normaldirection of the supporting member 10. The metal compound solutionhaving a composition shown in Table 4 may be prepared beforehand, or ametal compound solution containing no carbon-nanotube may be preparedbeforehand and the carbon-nanotube and the metal compound solution maybe mixed before the application. For improving dispersibility of thecarbon-nanotube, ultrasonic wave may be applied when the metal compoundsolution is prepared.

TABLE 4 Organic tin compound and 0.1-10 parts by weight organic indiumcompound Dispersing agent (sodium 0.1-5 parts by weight dodecylsulfate)Carbon-nanotube 0.1-20 parts by weight Butyl acetate Balance

When a solution of an organic tin compound dissolved in an acid is usedas an organic acid metal compound solution, tin oxide is obtained as amatrix. When a solution of an organic indium compound dissolved in anacid is used, indium oxide is obtained as a matrix. When a solution ofan organic zinc compound dissolved in an acid is used, zinc oxide isobtained as a matrix. When a solution of an organic antimony compounddissolved in an acid is used, antimony oxide is obtained as a matrix.When a solution of an organic antimony compound and an organic tincompound dissolved in an acid is used, antimony-tin oxide is obtained asa matrix. Further, when an organic tin compound is used as an organicmetal compound solution, tin oxide is obtained as a matrix. When anorganic indium compound is used, indium oxide is obtained as a matrix.When an organic zinc compound is used, zinc oxide is obtained as amatrix. When an organic antimony compound is used, antimony oxide isobtained as a matrix. When an organic antimony compound and an organictin compound are used, antimony-tin oxide is obtained as a matrix.Alternatively, a solution of metal chloride (for example, tin chlorideor indium chloride) may be used.

After the metal compound solution is dried, salient convexo-concaveshapes may be formed in the surface of the metal compound layer in somecases. In such cases, it is desirable to apply the metal compoundsolution again on the metal compound layer without heating thesupporting member 10.

[Step-B2]

Then, the metal compound composed of the organic acid metal compound isfired, to give an electron-emitting portion 17A having thecarbon-nanotubes 21 fixed onto the surface of the cathode electrode 11with the matrix 20 (which is specifically a metal oxide, and morespecifically, ITO) containing metal atoms (specifically, In and Sn)derived from the organic acid metal compound. The firing is carried outin an atmospheric atmosphere at 350° C. for 20 minutes. Thethus-obtained matrix 20 had a volume resistivity of 5×10⁻⁷ Ω·m. When theorganic acid metal compound is used as a starting material, the matrix20 made of ITO can be formed at a low firing temperature of as low as350 (C. The organic acid metal compound solution may be replaced with anorganic metal compound solution. When a solution of metal chloride (forexample, tin chloride and indium chloride) is used, the matrix 20 madeof ITO is formed while the tin chloride and indium chloride are oxidizedby the firing.

[Step-B3]

Then, a resist layer is formed on the entire surface, and the circularresist layer having a diameter, for example, of 10 μm is retained abovea desired region of the cathode electrode 11. The matrix 20 is etchedwith hydrochloric acid having a temperature of 10 to 60° C. for 1 to 30minutes, to remove an unnecessary portion of the electron-emittingportion. Further, when the carbon-nanotubes still remain in a regiondifferent from the desired region, the carbon-nanotubes are etched by anoxygen plasma etching treatment under a condition shown in Table 5. Abias power may be 0 W, i.e., direct current, while it is desirable toapply the bias power. The supporting member may be heated, for example,to approximately 80° C.

TABLE 5 Apparatus to be used RIE apparatus Gas to be introduced Gascontaining oxygen Plasma exciting power 500 W Bias power 0-150 WTreatment time period at least 10 seconds

Alternatively, the carbon-nanotubes can be etched by a wet etchingtreatment under a condition shown in Table 6.

TABLE 6 Solution to be used KMnO₄ Temperature 20-120° C. Treatment timeperiod 10 seconds-20 minutes

Then, the resist layer is removed, whereby a structure shown in FIG. 19Acan be obtained. It is not necessarily required to retain a circularelectron-emitting portion 17A having a diameter of 10 μm. For example,the electron-emitting portion 17A may be retained on the cathodeelectrode 11.

The process may be carried out in the order of [Step-B1], [Step-B3] and[Step-B2].

[Step-B4]

An insulating layer 12 is formed on the electron-emitting portion 17A,the supporting member 10 and the cathode electrode 11. Specifically, anapproximately 1 μm thick insulating layer 12 is formed on the entiresurface by a CVD method using, for example, tetraethoxysilane (TEOS) asa source gas.

[Step-B5]

Then, a stripe-shaped gate electrode 13 is formed on the insulatinglayer 12. Further, an insulating film 14 is formed on the insulatinglayer 12 and the gate electrode 13, and, a focus electrode 15 is formedon the insulating film 14. Then, a mask layer 22 is formed on the focuselectrode 15, then, an opening portion 16A is formed through the focuselectrode 15 and the insulating film 14, further, an opening portion 16Bis formed through the gate electrode 13, and, an opening portion 16Ccommunicating with the opening portion 16B formed through the gateelectrode 13 is formed through the insulating layer 12 (see FIG. 19B).When the matrix 20 is made of a metal oxide, for example, ITO, theinsulating layer 12 can be etched without etching the matrix 20. Thatis, the etching selective ratio between the insulating layer 12 and thematrix 18 is approximately infinite. The carbon-nanotubes 19 aretherefore not damaged when the insulating layer 12 is etched.

[Step-B6]

Then, preferably, part of the matrix 20 is removed under a conditionshown in Table 7, to obtain the carbon-nanotubes 21 in a state where topportions thereof are projected from the matrix 20. In this manner, theelectron-emitting portion 17A having a structure shown in FIG. 20A canbe obtained.

TABLE 7 Etching solution Hydrochloric acid Etching time period 10seconds-30 seconds Etching temperature 10-60° C.

Some or all of the carbon-nanotubes 21 may change in their surface statedue to the etching of the matrix 20 (for example, oxygen atoms or oxygenmolecules or fluorine atoms are adsorbed to their surfaces), and thecarbon-nanotubes 21 are deactivated with respect of electric fieldemission in some cases. Therefore, it is preferred to subject theelectron-emitting portion 17A to a plasma treatment in a hydrogen gasatmosphere. By the plasma treatment, the electron-emitting portion 17Ais activated, and the efficiency of emission of electrons from theelectron-emitting portion 17A is further improved. Table 8 shows anexample of a plasma treatment condition.

TABLE 8 Gas to be used H₂ = 100 sccm Source power 1000 W Power to beapplied to supporting 50 V member Reaction pressure 0.1 Pa Supportingmember temperature 300° C.

Then, for releasing gas from the carbon-nanotubes 21, a heatingtreatment or various plasma treatments may be carried out. For allowinga substance to be adsorbed to the surfaces of the carbon-nanotubes 21,the carbon-nanotubes 21 may be exposed to a gas containing the substancewhose adsorption is desirable. For purifying the carbon-nanotubes 21, anoxygen plasma treatment or a fluorine plasma treatment may be carriedout.

[Step-B7]

Then, the side wall surface of the opening portion 16C formed throughthe insulating layer 12 are allowed to recede by isotropic etching,which is preferred from the viewpoint of exposing the opening endportion of the gate electrode 13. Then, the mask layer 22 is removed,whereby a field emission device shown in FIG. 20B is completed.

The above process can be carried out in the order of [Step-B5],[Step-B7] and [Step-B6].

[Plane-type Field Emission Device (No. 2)]

FIG. 21A shows a schematic partial cross-sectional view of a plane-typefield emission device. The plane-type field emission device comprises acathode electrode 11 formed on a supporting member 10 made, for example,of glass, an insulating layer 12 formed on the supporting member 10 andthe cathode electrode 11, a gate electrode 13 formed on the insulatinglayer 12, an insulating film 14 formed on the gate electrode 13 and theinsulating layer 12, a focus electrode 15 formed on the insulating film14, an opening portion 16 formed through the focus electrode 15, theinsulating film 14, the gate electrode 13 and the insulating layer 12(an opening portion 16A formed through the focus electrode 15 and theinsulating film 14, an opening portion 16B formed through the gateelectrode 13, and an opening portion 16C formed through the insulatinglayer 12), and a flat electron-emitting portion (electron-emitting layer17B) formed on that portion of the cathode electrode 11 which ispositioned in the bottom portion of the opening portion 16. Theelectron-emitting layer 17B is formed on the stripe-shaped cathodeelectrode 11 extending in the direction perpendicular to the papersurface of the drawing. Further, the gate electrode 13 is extendingleftward and rightward on the paper surface of the drawing. The cathodeelectrode 11 and the gate electrode 13 are made of chromium.Specifically, the electron-emitting layer 17B is constituted of a thinlayer made of a graphite powder. In the plane-type field emission deviceshown in FIG. 21A, the electron-emitting layer 17B is formed on theentire region of the surface of the cathode electrode 11, while theplane-type field emission device shall not be limited to such astructure, and the point is that the electron-emitting layer 17B isformed at least in the bottom portion of the opening portion 16.

[Flat-type Field Emission Device]

FIG. 21B shows a schematic partial cross-sectional view of a flat-typefield emission device. The flat-type field emission device comprises astripe-shaped cathode electrode 11 formed on a supporting member 10made, for example, of glass, an insulating layer 12 formed on thesupporting member 10 and the cathode electrode 11, a stripe-shaped gateelectrode 13 formed on the insulating layer 12, an insulating film 14formed on the gate electrode 13 and the insulating layer 12, a focuselectrode 15 formed on the insulating film 14, and an opening portion 16formed through the focus electrode 15, the insulating film 14, the gateelectrode 13 and the insulating layer 12 (an opening portion 16A formedthrough the focus electrode 15 and the insulating film 14, an openingportion 16B formed through the gate electrode 13, and an opening portion16C formed through the insulating layer 12). The cathode electrode 11 isexposed in the bottom portion of the opening portion 16. The cathodeelectrode 11 is extending in the direction perpendicular to the papersurface of the drawing, and the gate electrode 13 is extending inleftward and rightward on the paper surface of the drawing. The cathodeelectrode 11 and the gate electrode 13 are made of chromium (Cr), andthe insulating layer 12 is made of SiO₂. That portion of the abovecathode electrode 11 which is exposed in the bottom portion of theopening portion 16 corresponds to an electron-emitting portion 17C.

[Method of Manufacturing an Anode Panel and a Display]

The method of manufacturing an anode panel AP will be explained belowwith reference to FIGS. 22A to 22F which are schematic partialcross-sectional views of a substrate, etc.

[Step-100]

First, a separation wall 33 is formed on a substrate 30 made of a glasssubstrate (see FIG. 22A). The plan form of the separation wall 33 is theform of a lattice (grid). Specifically, a lead glass layer colored inblack with a metal oxide such as cobalt oxide or the like is formed soas to have a thickness of approximately 50 μm, and then the lead glasslayer is selectively processed by photolithography and an etchingtechnique, whereby the separation wall 33 (see, for example, FIG. 3)having the form of a lattice (grid) can be obtained. There may beoptionally employed a constitution in which a glass paste having a lowmelting point is printed on the substrate 30 by a screen printingmethod, and then the glass paste having a low melting point is fired toform the separation wall, or a constitution in which a photosensitivepolyimide resin layer is formed on the entire surface of the substrate30, and then the photosensitive polyimide resin layer is exposed tolight and developed to form the separation wall. The separation wall 33in one pixel had length×width×height dimensions of 200 μm×100 μm×50 μm.Part of the separation wall works as a spacer holder for holding aspacer 34. Before the formation of the separation wall 33, preferably, ablack matrix (not shown in FIG. 22) is formed on the surface of thatportion of the substrate 30 which is a portion where the separation wall33 is to be formed, for improving displayed images in contrast.

[Step-110]

Then, for forming a phosphor layer 31R that emits light in red, forexample, a red-light-emitting phosphor slurry prepared by dispersing ared-light-emitting phosphor particles in a polyvinyl alcohol (PVA) resinand water and further adding ammonium bichromate is applied to theentire surface, and the applied red-light-emitting phosphor slurry isdried. Then, that portion of the red-light-emitting phosphor slurrywhich is a portion where the red-light-emitting phosphor layer 31R is tobe formed is irradiated to ultraviolet ray through the substrate 30 toexpose the red-light-emitting phosphor slurry. The red-light-emittingphosphor slurry is gradually cured from the substrate 30 side. Thethickness of the red-light-emitting phosphor layer 31R is determineddepending upon the dosage of ultraviolet ray to the red-light-emittingphosphor slurry. In this case, the red-light-emitting phosphor layer 31Rhad a thickness of approximately 8 μm, which was attained by adjustingthe time period of irradiation of the red-light-emitting phosphor slurrywith the ultraviolet ray. Then, the red-light-emitting phosphor slurryis developed, whereby the red-light-emitting phosphor layer 31R can beformed between predetermined separation walls 33 (see FIG. 22B).Thereafter, a green-light-emitting phosphor slurry is treated in thesame manner as above, to form a green-light-emitting phosphor layer 31G,and a blue-light-emitting phosphor slurry is treated in the same manneras above, to form a blue-light-emitting phosphor layer 31B (see FIG.22C). The surface of the phosphor layer 31 microscopically has aconvexoconcave shape formed by a plurality of the phosphor particles.The method of forming the phosphor layer is not limited to theabove-explained method. A red-light-emitting phosphor slurry, agreen-light-emitting phosphor slurry and a blue-light-emitting phosphorslurry may be consecutively applied, followed by consecutive exposuresand developments of the phosphor slurries to form each phosphor layer,or each phosphor layer may be formed by a screen printing method or thelike.

[Step-120]

Then, the substrate 30 having the separation walls 33 and the phosphorlayers 31 is immersed in a liquid (specifically, water) filled in atreatment vessel while the phosphor layer 31 is allowed to face theliquid surface side. A drain portion of the treatment vessel is closedin advance. And, an intermediate film 60 having a substantially flatsurface is formed on the liquid surface. Specifically, an organicsolvent in which a resin (lacquer) for constituting the intermediatefilm 60 is dissolved is dropped on the liquid surface. That is, anintermediate film material for forming the intermediate film 60 isspread on the liquid surface. The resin (lacquer) for constituting theintermediate film 60 is a kind of varnish in a broad sense, and itincludes a solution of a cellulose derivative, generally, a formulationcontaining nitrocellulose as a main component in a volatilizable solventsuch as a lower fatty acid ester, a urethane lacquer containing othersynthetic polymer and an acrylic lacquer. Then, in a state where theintermediate film material is floated on the liquid surface, theintermediate film material is dried, for example, for 2 minutes, wherebya film is made of the intermediate film material, and the intermediatefilm 60 having a flat surface is formed on the liquid surface. When theintermediate film 60 is formed, the amount of the intermediate filmmaterial to be spread is adjusted so that it has a thickness, forexample, of about 30 nm.

Then, the drain portion of the treatment vessel is opened, and theliquid is drained from the treatment vessel to lower the liquid surface,whereby the intermediate film 60 formed on the liquid surface movestoward the separation wall 33, comes in contact with the separation wall33 and finally comes into a state where the intermediate film 60 is incontact with the phosphor layers 31, and the intermediate film 60 isleft on the phosphor layers 31 (see FIG. 22D).

[Step-130]

Then, the intermediate film 60 is dried. That is, the substrate 30 istaken out of the treatment vessel, introduced into a drying furnace anddried in an environment having a predetermined temperature. Thetemperature for drying the intermediate film 60 is preferably in therange, for example, of 30° C. to 60° C., and the time period for dryingthe intermediate film 60 is preferably in the range, for example, ofseveral minutes to several tens minutes. The drying time period isnaturally decreased or increased depending upon the drying temperature.

[Step-140]

Then, an anode electrode 35 is formed on the intermediate film 60.Specifically, the anode electrode 35 made of a conductive material suchas aluminum (Al), chromium (Cr) or the like is formed so as to cover theintermediate film 60 by a vapor deposition method or a sputtering method(see FIG. 22E).

[Step-150]

Then, the intermediate film 60 is fired at about 400° C. (see FIG. 22F).The intermediate film 60 is combusted off by the above firing, and theanode electrode 35 remains on the phosphor layers 31 and the separationwalls 33. Gas generated by the combustion of the intermediate film 60 isdischarged to an outside through fine pores formed in that region of theanode electrode 35 which is bent along the form of the separation wall33. Since the pores are very fine, they do not cause any seriousinfluence on the structural strength of the anode electrode or on theproperty of image display.

[Step-160]

Then, a resistance layer 36, for example, made of ITO, is formed on theanode electrode 35 by a sputtering method. In this manner, the anodepanel AP can be completed.

[Step-170]

The cathode panel CP having a plurality of field emission devices isprepared. Then, the display is assembled. Specifically, a spacer 34 isattached on a spacer holding portion formed in the effective region ofthe anode panel AP. Then, the anode panel AP and the cathode panel CPare arranged such that the phosphor layer 31 and the electron-emittingregion face each other, and the anode panel AP and the cathode panel CP(more specifically, the substrate 30 and the supporting member 10) arebonded to each other in their circumferential portions through the frame40 made of ceramic or glass having a height of approximately 1 mm. Inthe bonding, a frit glass is applied to bonding portions of the frame 40and the anode panel AP and bonding portions of the frame 40 and thecathode panel CP. Then, the anode panel AP, the cathode panel CP and theframe 40 are attached. The frit glass (not shown) is pre-calcined orpre-sintered to be dried, and then fully calcined or sintered atapproximately 450° C. for 10 to 30 minutes. Then, a space surrounded bythe anode panel AP, the cathode panel CP, the frame 40 and the fritglass is vacuumed through a through-hole (not shown) and a tip tube (notshown), and when the space comes to have a pressure of approximately10⁻⁴ Pa, the tip tube is sealed by thermal fusion. In the above manner,the space surrounded by the anode panel AP, the cathode panel CP and theframe 40 can be vacuumed. Otherwise, for example, the frame 40, theanode panel AP and the cathode panel CP may be bonded in a high-vacuumatmosphere. Otherwise, the anode panel AP and the cathode panel CP maybe bonded with the adhesive layer alone without the frame depending uponthe structure of the display. Then, wiring to external circuits iscarried out to complete the display.

While the present invention has been explained on the basis of preferredExamples, the present invention shall not be limited thereto. Theconstitutions and structures explained with regard to the anode panel,the cathode panels, the displays and the field emission devices inExamples are given as examples and may be modified as required. Themanufacturing method explained with regard to the anode panel, thecathode panels, the displays and the field emission devices are given asexamples and may be modified as required. Further, the various materialsused in the manufacture of the anode panel and the cathode panels arealso given as examples and may be modified as required. With regard tothe display, color displays are explained as examples, while the displaymay be a monochromatic display.

In Example 1, the field emission device having the focus electrode hasbeen explained, while the focus electrode may be omitted. FIG. 23 showsa schematic partial end view of a display having such a constitution.

Generally, the above field emission device comprises:

-   (a) a cathode electrode 11 being formed on a supporting member 10    and extending in a first direction,-   (b) an insulating layer 12 formed on the supporting member 10 and    the cathode electrode 11,-   (c) a gate electrode 13 being formed on the insulating layer 12 and    extending in a second direction different from the first direction,-   (d) an opening portion formed through the gate electrode 13 and the    insulating layer 12 (an opening portion 16B formed through the gate    electrode 13 and an opening portion 16C formed through the    insulating layer 12), and-   (e) an electron-emitting portion 17 exposed in a bottom portion of    the opening portion 16C.

While the field emission device shown in FIG. 23 is a Spindt-type fieldemission device, the field emission device shall not be limited thereto.

As explained in Example 2, the cold cathode field emission display ofthe present invention may be any one of:

-   (1) a combination of the cold cathode field emission display    according to the first aspect of the present invention with the cold    cathode field emission display according to the third aspect of the    present invention,-   (2) a combination of the cold cathode field emission display    according to the first aspect of the present invention with the cold    cathode field emission display according to the fourth aspect of the    present invention,-   (3) a combination of the cold cathode field emission display    according to the second aspect of the present invention with the    cold cathode field emission display according to the third aspect of    the present invention, and-   (4) a combination of the cold cathode field emission display    according to the second aspect of the present invention with the    cold cathode field emission display according to the fourth aspect    of the present invention.

In the field emission device, there have been mostly explainedembodiments in which one electron-emitting portion corresponds to oneopening portion, while there may be employed an embodiment in which aplurality of electron-emitting portions correspond to one openingportion or one electron-emitting portion corresponds to a plurality ofopening portions, depending upon the structure of the field emissiondevice. Alternatively, there may be also employed an embodiment in whicha plurality of first opening portions are formed through a gateelectrode, a plurality of second opening portions communicating with aplurality of the first opening portion are formed through an insulatinglayer, and one or a plurality of electron-emitting portions are formed.

While the field emission devices in Examples have mainly explained aform in which one opening portion 16B formed through the gate electrode13 corresponds to one opening portion 16A formed through the focuselectrode 15 and the insulating film 14, some structures of the fieldemission device may use a form in which a plurality of opening portions16B formed through the gate electrode 13 correspond to one openingportion 16A formed through the focus electrode 15 and the insulatingfilm 14. That is, one opening portion 16A formed through the focuselectrode 15 and the insulating film 14 is provided in each electronemitting-region (each overlap region). FIGS. 24 and 25 show such a form.FIG. 24 is a schematic partial end view of such a display. FIG. 25 is ashowing of a layout state of the focus electrode 15, the opening portion16A formed through the focus electrode 15 and the opening portion 16Bformed through the gate electrode 13, and it is a schematic drawingobtained by viewing them from above. In FIG. 25, a dotted line shows thegate electrode 13 positioned below the focus electrode 15, and a chainline shows the cathode electrode 11. While a Spindt-type field emissiondevice is shown as a field emission device, a field emission devicehaving any other constitution may be employed.

In the display according to the present invention explained in Examples,the focus electrode may be replaced with a focus electrode which will beexplained hereinafter. That is, one example of the focus electrode canbe formed by forming an insulation film made, for example, of SiO₂ oneach surface of a metal sheet made, for example, of 42% Ni—Fe alloyhaving a thickness of several tens micrometers, and then forming openingportions in regions corresponding to pixels by punching or etching. And,the cathode panel, the metal sheet and the anode panel are stacked, aframe is arranged in the circumferential portions of the two panels, anda heat treatment is carried out to bond the insulation film formed onone surface of the metal sheet and the insulating layer 12 and to bondthe insulation layer formed on the other surface of the metal sheet andthe anode panel, whereby these members are integrated, followed byevacuating and sealing. In this manner, the display can be alsocompleted.

The gate electrode can be formed so as to have a form in which theeffective field is covered with one sheet of an electrically conductivematerial (having a opening portion). In this case, a positive voltage isapplied to the gate electrode. And, a switching element constituted, forexample, of TFT is provided between the cathode electrode constituting apixel and the cathode-electrode control circuit, and the voltageapplication state to the electron-emitting portion constituting thepixel is controlled by the operation of the above switching element, tocontrol the light emission state of the pixel.

Alternatively, the cathode electrode can be formed so as to have a formin which the effective field is covered with one sheet of anelectrically conductive material. In this case, a voltage is applied tothe cathode electrode. And, a switching element constituted, forexample, of TFT is provided between the electron-emitting portionconstituting a pixel and the gate-electrode control circuit, and thevoltage application state to the gate electrode constituting the pixelis controlled by the operation of the switching element, to control thelight emission state of the pixel.

In the display of the present invention, the relationship of the totalenergy “Q” required for vaporization of the resistance layer, theelectrostatic capacity “C” between the cold cathode field emissiondevice or the focus electrode and the anode electrode, and the voltageV_(A) applied to the anode electrode are defined, or the thickness t_(R)of the resistance layer, the capacity “C” between the cold cathode fieldemission device or the focus electrode and the anode electrode, and thevoltage V_(A) applied to the anode electrode are defined. As aconsequence, the occurrence of damage on the resistance layer andelements constituting the anode electrode and the cold cathode fieldemission device can be reliably suppressed even when a discharge takesplace between the cold cathode field emission device or the focuselectrode and the anode electrode. Moreover, the formation of theresistance layer can decrease the peak value of a discharge current. Asa result of these, there can be obtained cold cathode field emissiondisplays having excellent stability and reliability and having a longlifetime.

Further, the anode electrode may be divided into anode electrode unitshaving a smaller area in place of forming the anode electrode on theentire surface of the effective field. In this case, the electrostaticcapacity between each anode electrode unit and the cold cathode fieldemission device can be decreased, and the generation energy can bedecreased. As a result, the size of damage that a discharge causes onthe resistance layer or elements constituting the anode electrode andthe cold cathode field emission device can be more effectivelyminimized.

Further, generally, cold cathode field emission displays are subjectedto aging treatment immediately after their completion. The agingtreatment refers to a treatment that causes electron-emitting regions togradually emit electrons for brining the surfaces of theelectron-emitting regions into a state in which electrons are easilyemitted. Specifically, the voltage applied to the cathode electrode, thegate electrode and the anode electrode is gradually brought close to theoperation voltage of an actual cold cathode field emission display. Bythe above aging treatment, residual gas can be gradually released fromeach of elements constituting the cathode panel and the anode panel, andthe release of a large amount of gas from these elements at a time canbe prevented. During such aging treatment, an abnormal discharge isliable to take place between the anode electrode and the focuselectrode. In the cold cathode field emission display of the presentinvention, it is possible to reliably prevent the occurrence of damagethat the abnormal discharge between the anode electrode and the focuselectrode during the aging treatment causes on elements constituting thecold cathode field emission display.

1. A cold cathode field emission display comprising a cathode panelhaving a plurality of cold cathode field emission devices and an anodepanel which panels are bonded to each other in their circumferentialportions, the anode panel comprising a substrate, a phosphor layerformed on the substrate, an anode electrode formed on the phosphor layerand a resistance layer for controlling a discharge current, theresistance layer being formed on the anode electrode and having athickness of t_(R) (unit: μm), and the cold cathode field emissiondisplay satisfying the following expression (1),Q>(½)C·V _(A) ²  (1) whereQ ≈ π ⋅ t_(R) ⋅ r_(R)² ⋅ d_(R) × [C_(m_S)(T_(L) − T_(r)) + Q_(S_L) + C_(m_L)(T_(G) − T_(L)) + Q_(L_G)] × 10⁻⁶and, C: an electrostatic capacity (F) between the cold cathode fieldemission device and the anode electrode, V_(A): a voltage (V) to beapplied to the anode electrode, r_(R): a radius (mm) of avaporization-allowable region of the resistance layer, d_(R): a density(g·cm⁻³) of a material constituting the resistance layer, C_(m) _(—)_(S): a specific heat (J·g⁻¹·K⁻¹) of a material constituting theresistance layer in a solid state, T_(L): a melting point (° C.) of amaterial constituting the resistance layer, T_(r): room temperature (°C.), Q_(S) _(—) _(L): a heat of solution (J·g⁻¹) of a materialconstituting the resistance layer, C_(m) _(—) _(L): a specific heat(J·g⁻¹·K⁻¹) of a material constituting the resistance layer in a liquidstate, T_(G): a boiling point (° C.) of a material constituting theresistance layer, and, Q_(L) _(—) _(G): a heat of vaporization (J·g⁻¹)of a material constituting the resistance layer.
 2. The cold cathodefield emission display according to claim 1, in which the cold cathodefield emission device comprises: (a) a cathode electrode being formed onthe supporting member and extending in a first direction, (b) aninsulating layer formed on the supporting member and the cathodeelectrode, (c) a gate electrode being formed on the insulating layer andextending in a second direction different from the first direction, (d)an insulating film formed on the gate electrode and the insulatinglayer, (e) a focus electrode formed on the insulating film, (f) anopening portion formed through the focus electrode, the insulating film,the gate electrode and the insulating layer, and (g) anelectron-emitting portion exposed in a bottom portion of the openingportion.
 3. The cold cathode field emission display according to claim2, in which the cold cathode field emission device further comprises:(h) a second resistance layer for controlling a discharge current, thesecond resistance layer being formed on the focus electrode and having athickness of t′_(R) (unit: μm).
 4. The cold cathode field emissiondisplay according to claim 1, in which the cold cathode field emissiondevice comprises: (a) a cathode electrode being formed on a supportingmember and extending in a first direction, (b) an insulating layerformed on the supporting member and the cathode electrode, (c) a gateelectrode being formed on the insulating layer and extending in a seconddirection different from the first direction, (d) an opening portionformed through the gate electrode and the insulating layer, and (e) anelectron-emitting portion exposed in a bottom portion of the openingportion.
 5. The cold cathode field emission display according to claim1, in which the anode electrode is constituted of a set of N anodeelectrode units (N≧2), and said “C” represents an electrostatic capacity(unit: F) between the cold cathode field emission device and the anodeelectrode unit.
 6. A cold cathode field emission display comprising acathode panel having a plurality of cold cathode field emission devicesand an anode panel which panels are bonded to each other in theircircumferential portions, the anode panel comprising a substrate, aphosphor layer formed on the substrate, an anode electrode formed on thephosphor layer and a resistance layer for controlling a dischargecurrent, the resistance layer being formed on the anode electrode andhaving a thickness of t_(R) (unit: μm), and the cold cathode fieldemission display satisfying the following expression (1),Q>(½)C·V _(A) ²  (1) whereQ≈π·t _(R) ·r _(R) ² ·d _(R) ×[C _(m) _(—) _(S)(T _(G) −T _(r))+Q _(L)_(—) _(G)]×10⁻⁶ and, C: an electrostatic capacity (F) between the coldcathode field emission device and the anode electrode, V_(A): a voltage(V) to be applied to the anode electrode, r_(R): a radius (mm) of avaporization-allowable region of the resistance layer, d_(R): a density(g·cm⁻³) of a material constituting the resistance layer, C_(m) _(—)_(S): a specific heat (J·g⁻¹·K⁻¹) of a material constituting theresistance layer in a solid state, T_(r): room temperature (° C.),T_(G): a boiling point (° C.) of a material constituting the resistancelayer, and Q_(L) _(—) _(G): a sum (J·g⁻¹) of a heat of vaporization anda heat of solution of a material constituting the resistance layer. 7.The cold cathode field emission display according to claim 6, in whichthe cold cathode field emission device comprises: (a) a cathodeelectrode being formed on the supporting member and extending in a firstdirection, (b) an insulating layer formed on the supporting member andthe cathode electrode, (c) a gate electrode being formed on theinsulating layer and extending in a second direction different from thefirst direction, (d) an insulating film formed on the gate electrode andthe insulating layer, (e) a focus electrode formed on the insulatingfilm, (f) an opening portion formed through the focus electrode, theinsulating film, the gate electrode and the insulating layer, and (g) anelectron-emitting portion exposed in a bottom portion of the openingportion.
 8. The cold cathode field emission display according to claim7, in which the cold cathode field emission device further comprises:(h) a second resistance layer for controlling a discharge current, thesecond resistance layer being formed on the focus electrode and having athickness of t′_(R) (unit: μm).
 9. The cold cathode field emissiondisplay according to claim 6, in which the cold cathode field emissiondevice comprises: (a) a cathode electrode being formed on a supportingmember and extending in a first direction, (b) an insulating layerformed on the supporting member and the cathode electrode, (c) a gateelectrode being formed on the insulating layer and extending in a seconddirection different from the first direction, (d) an opening portionformed through the gate electrode and the insulating layer, and (e) anelectron-emitting portion exposed in a bottom portion of the openingportion.
 10. The cold cathode field emission display according to claim6, in which the anode electrode is constituted of a set of N anodeelectrode units (N≧2), and said “C” represents an electrostatic capacity(unit: F) between the cold cathode field emission device and the anodeelectrode unit.
 11. A cold cathode field emission display comprising acathode panel having a plurality of cold cathode field emission devicesand an anode panel which panels are bonded to each other in theircircumferential portions, the anode panel comprising a substrate, aphosphor layer formed on the substrate, an anode electrode formed on thephosphor layer and a resistance layer for controlling a dischargecurrent, the resistance layer being formed on the anode electrode andhaving a thickness of t_(R) (unit: μm), and the cold cathode fieldemission display satisfying the following expression (2),t _(R)×10⁻²>(½)C·V _(A) ²  (2) where C: an electrostatic capacity (F)between the cold cathode field emission device and the anode electrode,and V_(A): a voltage (V) to be applied to the anode electrode.
 12. Thecold cathode field emission display according to claim 11, in which thecold cathode field emission device comprises: (a) a cathode electrodebeing formed on the supporting member and extending in a firstdirection, (b) an insulating layer formed on the supporting member andthe cathode electrode, (c) a gate electrode being formed on theinsulating layer and extending in a second direction different from thefirst direction, (d) an insulating film formed on the gate electrode andthe insulating layer, (e) a focus electrode formed on the insulatingfilm, (f) an opening portion formed through the focus electrode, theinsulating film, the gate electrode and the insulating layer, and (g) anelectron-emitting portion exposed in a bottom portion of the openingportion.
 13. The cold cathode field emission display according to claim12, in which the cold cathode field emission device further comprises:(h) a second resistance layer for controlling a discharge current, thesecond resistance layer being formed on the focus electrode and having athickness of t′_(R) (unit: μm).
 14. The cold cathode field emissiondisplay according to claim 11, in which the cold cathode field emissiondevice comprises: (a) a cathode electrode being formed on a supportingmember and extending in a first direction, (b) an insulating layerformed on the supporting member and the cathode electrode, (c) a gateelectrode being formed on the insulating layer and extending in a seconddirection different from the first direction, (d) an opening portionformed through the gate electrode and the insulating layer, and (e) anelectron-emitting portion exposed in a bottom portion of the openingportion.
 15. The cold cathode field emission display according to claim11, in which the anode electrode is constituted of a set of N anodeelectrode units (N≧2), and said “C” represents an electrostatic capacity(unit: F) between the cold cathode field emission device and the anodeelectrode unit.
 16. A cold cathode field emission display comprising acathode panel having a plurality of cold cathode field emission devicesand an anode panel which panels are bonded to each other in theircircumferential portions, the anode panel comprising a substrate, aphosphor layer formed on the substrate and an anode electrode formed onthe phosphor layer, each cold cathode field emission device comprising:(A) a cathode electrode being formed on a supporting member andextending in a first direction, (B) an insulating layer formed on thesupporting member and the cathode electrode, (C) a gate electrode beingformed on the insulating layer and extending in a second directiondifferent from the first direction, (D) an insulating film formed on thegate electrode and the insulating layer, (E) a focus electrode formed onthe insulating film, (F) a resistance layer for controlling a dischargecurrent, the resistance layer being formed on the focus electrode andhaving a thickness of t_(R) (unit: μm), (G) an opening portion formedthrough the focus electrode, the insulating film, the gate electrode andthe insulating layer, and (H) an electron-emitting portion exposed in abottom portion of the opening portion, and the cold cathode fieldemission display satisfying the following expression (3),Q>(½)C·V _(A) ²  (3) whereQ ≈ π ⋅ t_(R) ⋅ r_(R)² ⋅ d_(R) × [C_(m_S)(T_(L) − T_(r)) + Q_(S_L) + C_(m_L)(T_(G) − T_(L)) + Q_(L_G)] × 10⁻⁶and, C: an electrostatic capacity (F) between the focus electrode andthe anode electrode, V_(A): a voltage (V) to be applied to the anodeelectrode, r_(R): a radius (mm) of a vaporization-allowable region ofthe resistance layer, d_(R): a density (g·cm⁻³) of a materialconstituting the resistance layer, C_(m) _(—) _(S): a specific heat(J·g⁻¹·K⁻¹) of a material constituting the resistance layer in a solidstate, T_(L): a melting point (° C.) of a material constituting theresistance layer, T_(r): room temperature (° C.), Q_(S) _(—) _(L): aheat of solution (J·g⁻¹) of a material constituting the resistancelayer, C_(m) _(—) _(L): a specific heat (J·g⁻¹·K⁻¹) of a materialconstituting the resistance layer in a liquid state, T_(G): a boilingpoint (° C.) of a material constituting the resistance layer, and Q_(L)_(—) _(G): a heat of vaporization (J·g⁻¹) of a material constituting theresistance layer.
 17. The cold cathode field emission display accordingto claim 16, in which the anode electrode is constituted of a set of Nanode electrode units (N≧2), and said “C” represents an electrostaticcapacity (unit: F) between the focus electrode and the anode electrodeunit.
 18. A cold cathode field emission display comprising a cathodepanel having a plurality of cold cathode field emission devices and ananode panel which panels are bonded to each other in theircircumferential portions, the anode panel comprising a substrate, aphosphor layer formed on the substrate and an anode electrode formed onthe phosphor layer, each cold cathode field emission device comprising:(A) a cathode electrode being formed on a supporting member andextending in a first direction, (B) an insulating layer formed on thesupporting member and the cathode electrode, (C) a gate electrode beingformed on the insulating layer and extending in a second directiondifferent from the first direction, (D) an insulating film formed on thegate electrode and the insulating layer, (E) a focus electrode formed onthe insulating film, (F) a resistance layer for controlling a dischargecurrent, the resistance layer being formed on the focus electrode andhaving a thickness of t_(R) (unit: μm), (G) an opening portion formedthrough the focus electrode, the insulating film, the gate electrode andthe insulating layer, and (H) an electron-emitting portion exposed in abottom portion of the opening portion, and the cold cathode fieldemission display satisfying the following expression (3),Q>(½)C·V _(A) ²  (3) whereQ≈π·t _(R) ·r _(R) ² ·d _(R) ×[C _(m) _(—) _(S)(T _(G) −T _(r))+Q _(L)_(—) _(G)]×10⁻⁶ and, C: an electrostatic capacity (F) between the focuselectrode and the anode electrode, V_(A): a voltage (V) to be applied tothe anode electrode, r_(R): a radius (mm) of a vaporization-allowableregion of the resistance layer, d_(R): a density (g·cm⁻³) of a materialconstituting the resistance layer, C_(m) _(—) _(S): a specific heat(J·g⁻¹·K⁻¹) of a material constituting the resistance layer in a solidstate, T_(r): room temperature (° C.), T_(G): a boiling point (° C.) ofa material constituting the resistance layer, and Q_(L) _(—) _(G): a sum(J·g⁻¹) of a heat of vaporization and a heat of solution of a materialconstituting the resistance layer.
 19. The cold cathode field emissiondisplay according to claim 18, in which the anode electrode isconstituted of a set of N anode electrode units (N≧2), and said “C”represents an electrostatic capacity (unit: F) between the focuselectrode and the anode electrode unit.
 20. A cold cathode fieldemission display comprising a cathode panel having a plurality of coldcathode field emission devices and an anode panel which panels arebonded to each other in their circumferential portions, the anode panelcomprising a substrate, a phosphor layer formed on the substrate and ananode electrode formed on the phosphor layer, each cold cathode fieldemission device comprising: (A) a cathode electrode being formed on asupporting member and extending in a first direction, (B) an insulatinglayer formed on the supporting member and the cathode electrode, (C) agate electrode being formed on the insulating layer and extending in asecond direction different from the first direction, (D) an insulatingfilm formed on the gate electrode and the insulating layer, (E) a focuselectrode formed on the insulating film, (F) a resistance layer forcontrolling a discharge current, the resistance layer being formed onthe focus electrode and having a thickness of t_(R) (unit: μm), (G) anopening portion formed through the focus electrode, the insulating film,the gate electrode and the insulating layer, and (H) anelectron-emitting portion exposed in a bottom portion of the openingportion, and the cold cathode field emission display satisfying thefollowing expression (4),t _(R)×10⁻²>(½)C·V _(A) ²  (4) where C: an electrostatic capacity (F)between the focus electrode and the anode electrode, and V_(A): avoltage (V) to be applied to the anode electrode.
 21. The cold cathodefield emission display according to claim 20, in which the anodeelectrode is constituted of a set of N anode electrode units (N≧2), andsaid “C” represents an electrostatic capacity (unit: F) between thefocus electrode and the anode electrode unit.